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AMERICAN 
FOREST REGULATION 



BY 

THEODORE SALISBURY WOOLSEY, Jr., M.F. 

Author of Studies in French Forestry, etc. 

Consulting Forester; Assistant District Forester, Forest Service 1908-1915; 

Lecturer Yale School of Forestry, 1912, 1916-1917 



THE TUTTLE, MOREHOUSE AND TAYLOR COMPANY 
NEW HAVEN, CONNECTICUT 



/yz- ^■■■^ 



7 






Copyright 1922 

Part I and appendix, Theodore S. Woolsey, Jr. 

Part II, Herman H. Chapman 



MAV I J 1922 
g)C!,A674209 



TO 

JAMES W. TOUMEY 

IN RECOGNITION OF HIS SERVICES 

AS A TEACHER OF FORESTRY 

IN THE YALE SCHOOL OF FORESTRY 



PREFACE 



"American Forest Regulation" is intended primarily as a textbook on the 
theory and application of regulating the cut. It may also serve as a guide 
to forest administrators who must solve broad regulation problems at a 
reasonable cost. Emphasis has been placed on the discrimination and choice 
of material, rather than the collection and elaboration of a multitude of 
methods — many totally unsuited to American conditions. Forest manage- 
ment in the United States cannot be successful until it is definitely recognized 
that the cutting on all forests held for permanent production must be con- 
trolled by working plans based on sound silviculture, local economic require- 
ments and rate of yield. 

Not the least perplexing of the problems encountered has been the question 
of terminology. The author, a member of the Committee of the Society of 
American Foresters, which recommended standard terms* and definitions, 
has followed the Committee's report, except where it departs from well 
established common usage. "Working circle" has accordingly been substi- 
tuted for "working unit." The student who is assigned additional reading 
or study in the works of other authors, cannot help but be confused by a 
varying use of terms. For example, "working group" may be termed "work- 
ing section" by one author, "working figure" by another, and "working circle" 
by a third. The "working unit" of the S. A. F. again may be described as 
"working circle" by Sir William Schlich**, thus further perplexing the student. 
The writer felt that no personal preference for terms should enter into this 
new book on American Forest Regulation but that "working circle," widely 
used in the United States, was preferable to "working unit." On the other 
hand, the new term "management plan," largely used by the Forest Service 
in place of the term "working plan" (adopted for generations by English 
speaking foresters), has not been adopted. 

To simplify study, the regulation of cut methods in Part I have been treated 
systematically, as follows: (i) Definition, (2) Discussion, (3) Illustration, 
(4) Class room questions or quiz. This plan has not been rigidly adhered 
to, yet so far as the subject matter lends itself to this form of treatment, it 
is used throughout. Formulae have first been stated in English (instead of 
in "formulae equivalents") because the writer found they were more readily 
grasped by the student. A special feature is quite complete foot-note refer- 
ences to American Literature on each subject. 

A rather theoretical discussion of soil-rent (after Endres) has been given, 
notwithstanding the fact that it is likely that a large proportion of the best 
American forests will eventually be owned or controlled by the public, and 
consequently need not necessarily be managed strictly on the basis of the 



* Published 1917 in the Journal of Forestry, Vol. XV, No. i. 

**Schlich, Sir William, Manual of Forestry (Forest Management, Vol. 3, p. 273). 



vi American Forest Regulation 

highest soil-rent. Yet this financial side may eventually be of weight in 
planning the management of many private American forests, where business 
reasons may usually be foremost. Because of this considerable space in the 
appendix has been given to a frankly Germanized explanation of soil-rent, 
and to Endres' discussion and illustration of its application. 

The contrast between French and German text-book methods is evident 
even to the casual reader. The German is apt to treat the subject exhaus- 
tively; he will describe twenty different formulae, each varying from the 
other ever so little, while the French writer will perhaps narrow the formulae 
down to three fundamental and radically different methods, and omit the 
others. This book (with the exception of soil-rent) has been written from the 
French rather than from the German viewpoint, and, consequently, may err in 
its simplicity rather than in the complexity of subject matter. Commenting on 
this very feature of German thoroughness and complexity. Sir William 
Schlich states:* 

"Of the seventeen methods described several have only an academic interest, if so 
much, and all of the others have for their object to secure a sustained yield by gradually 
producing such a proportion between the different age classes that each shall, as nearly 
as possible, occupy about the same area, w^hether they are found on different areas or 
scattered over the whole forest .... there is not nearly so much difference in the 
several methods as their inventors believe." 

This viewpoint explains why the author of this volume has omitted the 
usual elaboration of textbook methods and formulae which differ from each 
other in some minor degree. 

Rather than include data on American working plans which are untried 
and preliminary in character, the writer has omitted the usual treatment of 
this phase of organization. In Appendix A — E some "working plan" data 
have necessarily been included so as not to mar a complete translation of a 
portion of Martin's Forsteinrichtung. 

Acknowledgment has been made in the foot-notes for material borrowed 
directly from other sources, but necessarily many of the ideas and much 
of the data included, have been absorbed and adapted from text-books on the 
same subject, especially from Volume III (Fourth edition) Manual of Forestry 
by Sir William Schlich ; from Lehrbuch Waldwertrechung and Forststatik 
by Max Endres; and from Volume III, Economic Forestiere by G. Fluffel. 
The description of regulation in the various German states and in Austria 
given in the appendix is translated from Martin's Forsteinrichtung. Acknowl- 
edgment is also due C. E. Carter (of Australia), Yale School of Forestry, 
1922, T. S. Hansen, Yale School of Forestry, 1917, T. T. Munger, U. S. F. S., 
E. J. Hanzlik, U. S. F. S., E. Koch, U. S. F. S., and M. H. Wolff, U. S. F. S., 
for a review of and a critical comment on the manuscript of Part I. 

When the original plan of February i, 1917 of publishing under joint author- 
ship with Professor Chapman had to be abandoned, the following acknowl- 
edgment was agreed upon : 

"This manuscript was (largely) written in 1917, with the consent and cooperation of 
H. H. Chapman. The technical order and arrangement followed the Yale lecture notes 



Sir William Schlich (Quarterly Journal of Forestry. 1913, p. 201). 



Preface vii 

of Prof. Chapman, but the American and European details and references and scheme 
of treatment, are original with the writer. Tlie manuscript was revised and completed 
by the writer in 1920 (1921). While Prof. Chapman assumes no responsibility, what- 
soever, as to technical details, the writer wishes to acknowledge his very great indebted- 
ness to him for the use of his notes as a guide. Those who took his lectures at Yale 
will recognize just how great this indebtedness is." 

In 1920 Prof. Chapman kindly agreed to contribute Part II on "Correlation 
of Regulation and Growth in Extensive American Forests," with the under- 
standing that the book would be immediately published under my authorship. 
The slight duplication of Part I in Part TI is an advantage rather than a 
detriment and Chapman's comment on the correlation of growth and regula- 
tion is invaluable. 

When chief of silviculture in the Forest Service, District No. 3, the need 
for regulating the cut of timber on National Forests was very apparent. 
After giving the courses in management at the Yale School of Forestry, 1916- 
17 (when Professor Chapman took my place in the West) I was convinced 
that regulation had been misunderstood and neglected in the United States 
and that, therefore, there was an immediate need of a thoroughly Americanized 
edition on this essential and important phase of forest management. The 
opportunity of service with the A. E.' F. in France explains the four years 
delay in publication, but I am certain that the need for such a book to-day is 
all the more acute. 

Theodore S. Woolsey, Jr. 
New Haven, Conn. 

December, 1921. 



PART I 
POLICY AND THEORY OF REGULATION 

CHAPTER I 

INTRODUCTION TO FOREST REGULATION 

Page 

1. Definition and Significance of Forest Regulation i 

2. Conception of Regulation in Europe 3 

3. Scope of Regulation 4 

4. Land Classification, an Initial Step 4 

5. Details Must be Systematized in Working Plans 5 

6. Progress of American Regulation in Early Working Plans 5 

Stock Taking by the Forest Service Preliminary to Regulation 6 

Regulation on Privately Owned Property 7 

Quiz 7 

CHAPTER II 
BACKGROUND OF A REGULATION POLICY AND SUSTAINED YIELD 

10. Basic Conditions that Show Need for the Conservation and Regulation of Forests 9 

11. Basic Studies 10 

12. Curtailment of Production ? 10 

13. Continuous Forest Production 1 1 

14. Early Western Land Policy and Its Results 11 

15. Effect of Economic Lumbering on Forest Management 12 

16. Possible Solutions ; Restricted Private Control or Public Ownership? 13 

17. Policy and Definition of Sustained Yield 14 

18. Comparison with Conditions in France 15 

19. Financial Aspect of a Sustained Yield 15 

20. Sustained Yield on Public Forests 16 

21. Sustained Yield Objectives and Difficulties in Practice 17 

22. Summary of Limitations on a Sustained Yield Policy 17 

23. Quiz 18 

CHAPTER III 
MANAGEMENT AND ADMINISTRATIVE SUBDIVISIONS 

24. Definition of and Size of Subdivisions 20 

25. Definition of Management Subdivisions 20 

26. Discussion of Management Subdivisions 21 

27. Factors that Justify Formation of Working Groups 22 

28. Working Circles 23 

29. Policy of Small or Large Working Circles 24 

30. Definitions of Block, Compartment and Lot 24 

31. Discussion of Block, Compartment and Lot 25 

32. Definition of Administrative Subdivisions 26 

ZZ- Discussion of Administrative Subdivisions 26 

34- Quiz 26 



Contents ix 

CHAPTER IV 
ROTATIONS-TECHNICAL, SILVICULTURAL, AND ECONOMIC 

Page 

Definitions of Rotation (and Felling Age) 28 

Not to be Confused with Cutting Cycle 29 

Conception of Length of Rotation 29 

Basic Policy for Rotations 3° 

Mean Rotations for an Entire Stand 30 

Kinds of Rotations 30 

Definition and Discussion of Technical Rotations 31 

Illustrations of Technical Rotations 3i . 

Definition and Discussion of Silvicultural Rotations , 32 

Illustrations of Silvicultural Rotation Limits 33 

Definition and Discussion of Economic or Quantitative Rotations 34 

Choice of Economic Rotation with Illustrations 35 

Quiz 38 

CHAPTER V 
FINANCIAL ROTATIONS 

48. . Definition of Financial Rotations and Related Subjects 39 

49. (A) Rotations for Maximum Forest Rent or Highest Mean Annual Net Money 

Return 40 

50. Illustrations of Alaximum Forest Rent 40 

51. Distinction Between Forest Rent and Soil Rent with Illustrations 41 

52. (B) Rotations for Maximmn Soil Rent or Highest Returns per Dollar Invested .. 43 
53- (a) What Rate of Interest Should Be Used ? 44 

54. (b) What is Influence of Final Yield? 45 

55. Illustrations of American Attempts at Calculating Maximum Soil Rent Rotations . . 46 

56. Final Choice of a Rotation 51 

57. Summary of Principles Affecting Length of Rotations 52 

58. Quiz 54 

CHAPTER VI 
THE NORMAL FOREST 

59. Definitions of Normal Forest, Normal Increment 56 

60. Discussion of the Normal Forest 56 

61. Three Phases of Abnormality 56 

62. A Normal Distribution of Age Classes 57 

63. Artificial and Natural Factors Influencing Distribution of Age Classes 57 

64. Normal Increment 58 

65. Normal Growing Stock 58 

66. Growing Stock Formulae 59 

67. Illustration of Simplest Normal Growing Stock Calculation 61 

68. Yield Table Method of Computing Growing Stock 62 

69. Illustration of Calculating Normal Growing Stock from Yield Table 62 

70. Comparison of Normal Growing Stock Formulae 64 

71. Illustrations of Munger Formula 64 

72. Flury's Normal Stock Formula with Illustration 65 

73. A Normal Stock Calculation in Lodgepole Pine 65 

74. Importance of Normal Growing Stock in the United States 66 

75- Quiz 65 



X American Forest Regulation 

CHAPTER VII 

REGULATING THE CUT 

Page 

76. Definition and Aims of Regulating the Cut 68 

77. Basic Policy in Regulating the Cut 68 

78. To Attain Regulation Compromises are Necessary 70 

79. Relation between Increment and Growing Stock 70 

80. Definitions and Classification of Methods of Regulating the Cut 71 

CHAPTER VIII 
(A) VOLUME METHODS OF REGULATION 

81. General Principles and Classification of Volume Methods 74 

82. ( I ) Volume Regulation Based on Growing Stock 75 

83. (2) Volume Regulation Based on Increment Alone 78 

84. (3) Volume Regulation Based on Growing Stock and Increment 79 

85. (a) The Modified Austrian Formula 80 

86. (4) Volume Regulation Based (on Growing Stock) and Size Classes (and Periods) 82 

87. Discussion of French Method of 1883 82 

88. Illustration of French Metliod of 1883 85 

89. (5) Volume Regulation Based on the Tree as a Unit; (a) Indian Single Tree 

Method (Brandis) 86 

90. (b) Diameter Limit (Pinchot-Graves) 88 

91. Quiz 89 

CHAPTER IX 
(B) AREA, AND (C) AREA-VOLUME METHODS OF REGULATION 

92. Value and Classification of (B) Area Methods ,90 

93. (i) Fixed Area as a Basis for Regulation of Cut 90 

94. Illustration of Fixed Area for Limiting the Cut 91 

95. (2) Area Allotment by Periods as a Basis for Regulation 91 

96. Use of Yield Tallies in Computing Volumes 92 

97. (C) Area- Volume (and Age) Basis of Regulation — Value and Classification 93 

98. (i) Volume and Area- Volume (and Age) Allotment as a Basis for Regulation ... 93 

99. Modern Allotment Principles 94 

100. Regulation by (Americanized) Stand Selection (after Judeich) 95 

lOi. Illustrations of Stand Selection in Eastern and Western Forests 95 

102. Differences between Area-Volume Allotment and Stand Method 100 

103*. Use of Age Classes in Regulation loi 

104. Regulation on Basis of Cutting Cycles and Felling Reserve loi 

105. Quiz 103 

PART II 

CORRELATION OF REGULATION AND GROWTFI IN EXTENSIVE 
AMERICAN FORESTS 

CHAPTER X 
THE CUTTING CYCLE AS A DETERMINING INFLUENCE 

IN AMERICAN FOREST REGULATION 

Page 

106. Attitude of Private Owners 105 

107. Preliminary Requirements 10:5 

108. Obstacles to Regulation of Yield 106 



Contents xi 

Page 

Policy as Influenced by Character of Ownership 107 

Goal of Public Management 108 

Influences Determining Initial Cut per Acre 108 

The Cutting Cycle ; Definition ; Length 109 

Growth on Cut-Over Lands 109 

Growth on Virgin Forests ; Intermittent Yields no 

Relation between the Cut Per Acre and the Cutting Cycle no 

Similarity of Even-Aged and Alany-Aged Forests m 

Residual Growing Stock and Felling Reserve 112 

Illustration of a Transition Cutting Cycle in a Normal Forest 112 

Ultimate Form of the Forest 1 13 

Principle of Allotment of Definite Stands for Cutting During Period 114 

Principle of a Horizontal Cut to Fixed Limits of Age or Size 114 

Application of These Two Principles in Contracts for the Purchase of Timber 

Cutting Rights 115 

Eflfect of a Surplus of Over-mature Timber upon the Minimum Exploitable Age . . 116 

Desirability of Short Cutting Cycles when Possible 117 

Necessity for Horizontal Cut and Long Cutting Cycles for Virgin Forests 117 

Illustration of Application of Principles to Western Yellow Pine 118 

Basis of Computing the Annual Cut by the Principle of a Horizontal Cut 119 

Ouiz 122 



CHAPTER XI 
THE APPLICATION OF REGULATION TO AMERICAN FORESTS 

129. Resume of Principles 123 

130. Application of These Principles to American Forests 125 

131. Preliminary Cutting Cj'cle for Valuable Species in Mixed Forests 125 

132. Transition Cutting Cycle; Examples of Intermittent Yields under Forest Man- 

agement 126 

133. Assumption that Growth Balances Decadence 127 

134. Formula for Regulation of Cut Based on This Assimiption 127 

135. Illustration, Coconino National Forest 128 

136. Comparison with Von Mantel's Formula 128 

137. Illustration, Munger, Western Yellov/ Pine in Oregon. First Cutting Cycle 129 

138. Summary of Principles i33 

139. Separation of the Forest into Age Classes 134 

140. Siunmary of Possible Conditions I35 

141. Illustration from Tusayan National Forest 136 

142. For Many-Aged Stands i37 

143. Illustration from Yellow Poplar in Tennessee 138 

144. A System of Regulation of Yield for Alany-Aged or Selection Forests Based on 

Diameters and Diameter Growth, Preliminary in Character and Dispensing with 

the Yield Table I39 

145. Illustration with Scattered Shortleaf and Loblolly Pine Growing with Mixed Hard- 

woods ( Southern States) I39 

146. Factor of Loss of Numbers 140 

147. Determination of Normality 141 

148. Overcutting 142 

149. Method of Regulating Yield I43 

150. Comparison with French System of 1883 I43 

151. Summary of Distinctive Characteristics of American Regulation I45 

152. Quiz 146 



xii Auicrica)i Forest Regulation 

CHAPTER XII 

THE PROBLEM OF SUSTAINED YIELD 

Page 

153. The Ultimate Problem — Sustained Yield 147 

154. Allowed Cut, Empirical Yield Table and Normal Stock 147 

155. Comparison of Mean Annual Increment and Austrian Formula; Its Limitations ... 149 

156. Necessity for Data on Age Classes 151 

157. A Method of Separation of Age Classes 151 

158. Application of Yield Table to tlie Forest 152 

159. Separation of Stand Table into Age Classes 153 

160. Average Age of Groups 1 54 

161. Illustration from Coconino National Forest 157 

162. Immature Age Classes 157 

163. The Prediction of Actual or Empirical Yields for the Forest 159 

164. Application to Group Selection Forests 160 

165. Coordination of Cutting Cycle with Area and Volume of Existing Age Classes .... 161 

166. Comparison of Annual Cut by Methods of Regulation Proposed 162 

167. Summary of Basic Principles 163 

168. Factors Indicating a Shortening of the Cutting Cycle ; Illustrations 164 

169. Quiz 165 

CHAPTER XIII 
REGULATION OF FORESTS COMPOSED OF EVEN-AGED STANDS 

170. Regulation of Forests Composed of Even-Aged Sfands i6t 

171. Similarity of Problem with That of Many-Aged Forms 166 

172. Application to Eastern Mixed Hardwoods 166 

173. Prediction of Yields of Mixed Hardwoods 168 

174. Correlation of Regulation with Methods Proposed 169 

175. Coordination of Regulation with the Silvicultural Practice 170 

176. Illustration, Lodgepole Pine 170 

177. Summary of Principles for American Regulation 173 

178. Quiz 174 

APPENDIX 

A. (a) Forest Management in Nine European States (after Martin) 178 

(b) Financial Rotations (after Endres) 200 

B. Growing Stock and Yield, Harvard Forest 204 

C. Example of a Preliminary Policy Statement for Inyo National Forest 205 

D. Results of Forest Management in Savoie, France 208 

E. Examples of Yield Calculations from National Forest "Management Plans," 1921 . . . 210 

F. Comment on Wolff Formula 212 



SYMBOLS USED 

Symbol Equivalent 

Gn Normal growing stock. 

Ga Real or actual growing stock, 

n Normal, 

r Rotation, 

r' The difference between the age when the tree reaches merchantable size and 

the rotation age. 

s Age when tree reaches merchantable size. 

i Increment (c. a. i. and m. a. i. are symbols for current and mean annual increment). 

N Number of years. 

Yn Normal yield. 

Ya Real or actual yield. 

X Number of years within which to distribute the surplus or deficit. 

M% Mortality per cent (M is the symbol for Gernxan marks in appendix A). 

M ft. 1,000 feet board measure, 

cc Cutting cycle. 

Res. Timber reserved after cutting. 

F$ Final yield (in dollars). 

1$ Intermediate yield (in dollars). 

E$ Expenditures (if annual, symbol is AE$) capitalized. 

C$ Costs (initial). 

a, b, etc. Yield table figure for yield at lo years, 20 years, etc. 

A Area. 



TABLES 
Table Page 

1. Economic Rotation for Pine, Spruce, Fir and Beech in Europe 35 

2. Synopsis of Gross Returns, Expenditures, and Mean Annual Net Returns in Dollars 

Per Acre for a Fully Stocked Quality III Spruce Stand 40 

3. Rate of Interest Earned in European Forestry 45 

4. Value of Fully Stocked Stands of Loblolly Pine, etc 47 

5. Cost of Growing Cordwood in Fully Stocked Stands of Loblolly Pine, etc 48 

6. Interest Rates (Compound) to be Expected on Money Invested in Growing Ash, etc. 49 

7. The Financial Rotation of White Pine 50 

8a. Soil Expectation Value for Douglas Fir, Quality II Site, Western Cascades 50-51 

8. Yield of White Pine in New Hampshire 63 

9. Normal Growing Stock in Board Feet Per Acre for Rotations of 20 to 60 Years by 

Different Formulae 64 

ID. Real and Normal Growing Stock and Periodic Annual Increment, etc 65 

11. Relative Classification of Methods for Regulating the Cut Used by Different Writers ^2 

12. List of Formulae Omitted from Text 72 

13. Distinctions between Formulae Based on Growing Stock and Increment 79 

14. Number of Trees in Different Diameter Classes Per Acre Required to Obtain a 

Continuous Yield from a Fully Stocked Group Selection Stand of Pure Poplar . . 138 

15. Empirical Yield Table of Western Yellow Pine Reduced from Normal by Factor 

66.2% 148 

16. Yield Table for Bernice Division, Deerlodge National Forest. Lodgepole Pine, 

Reduction to 33/6% 171 



FIGURES 

1. Relation of Regulation to Other Subjects 4 

2. Diagrammatic Sketch Map Illustrating the Distinction between Working Group and 

Working Circle ( Syn., Working Unit) 21 

3. Diagrammatic Representation of Normal Growing Stock, etc 59 

3a. Proof of Wolff Formula 61 

4. Diagrammatic Scheme of the Yield Table Yields 62 

5. Illustration of the Result of Using a Correction Factor for Von Mantel's Formula . . 76 

6. Illustration of Residual Growing Stock, Felling Reserve, and Surplus 120 

7. Volume of Western Yellow Pine, Distributed by Diameter Classes, Coconino National 

Forest 154 



INTRODUCTORY 



By B. E. Fernow 



The question is sometimes raised — even in professional circles — whether 
silviculture or forest regulation (organization) is the more important subject. 
To raise this question is like inquiring whether the shelves in the library are 
more important than the books, the implements used in raising a crop more 
important than the crop itself. Nevertheless as suggested by ^sop's noted 
fable on the quarrel of the members, forest regulation (organization) is abso- 
lutely essential for a well conducted forestry business, just as the systematic 
management of a factory is all important to the success of that business. 

In applying the various methods of regulation, the needs of silvicultural 
operations must necessarily produce modifications of the mathematics 
involved in regulating the felling budget. How far these silvicultural con- 
siderations are to influence the economic considerations will depend upon the 
character and the interests of the owner. For instance for forests under State 
ownership the interests of the future could and should dominate and more 
economic or financial sacrifices may be justified in attaining the normal forest 
than is the case in private ownership. The conditions for an economic sus- 
tained yield may be more rapidly attempted by the former, while the latter 
may be satisfied with a mere silvicultural sustained yield, i.e., keeping the land 
in forest. Conditions vary so greatly that it is impossible to lay down princi- 
ples. Compromises will be necessary which depend upon the financial ability 
and other modifying circumstances of the owner. 

The forestry business has an advantage over most other businesses in that 
it has its ideal formulated, namely in the normal forest (with its normal grow- 
ing stock, age class gradation, and distribution, and normal increment), con- 
sciously and expressed or unconsciously and unexpressed. As with all ideals, 
practical considerations and conditions keep us from attaining them fully, and 
the problem for the forester is always how far he will sacrifice present advan- 
tages to this ideal of the sustained yield forest. 

It should be borne in mind that the European methods of regulation repre- 
sent a historic evolutionary series, each one having acceptable features which 
are borrowed by the next. With modern means of transportation, the need of 
making any small forest completely normal has become less imperative and 
has permitted the freedom of handling it a la Judeich. Moreover the exten- 
sive application of the division and allotment methods had brought about the 
existence of suitable age classes when the stand method became practicable. 

Although only one state (Baden) has adopted the Karl Heyer (see para- 
graph 85) method of regulating the forest, I am inchned to consider this 
method the most practical in attaining a normal forest condition without too 
much sacrifice if carried out in Heyer's spirit. It will also be applicable in the 
United States in many cases. 

The effort of investigating the applicability of European methods and of 
developing American methods, as attempted in this volume, is one which is 
worthv of all praise. -d t- t- 

^ B. E. i^ERNOW. 

December, 1921. 



PART I 



POLICY AND THEORY OF REGULATION 



CHAPTER I 
INTRODUCTION TO FOREST REGULATION 

I. Definition and Significance of Forest Regulation. Forest Regulation* 
(syn. organization) is that branch of forestry zvhich concerns itself with the 
organization of a forest property for management and maintenance, ordering in 
time and place the most advantageous use of the property, with the aim of securing 
a sustained yield. The broader term forest management includes all subjects 
dealing with the inventory, condition, and proper and systematic development 
of forest resources, and the organization and administration which will secure 
their continuous productiveness. Regulation aims chiefly at continuity of pro- 
ductiveness but also at utilizing to the fullest extent the resources under forest 
management; the normal timber capital is property held in trust, while the cut 
constitutes the ozvner's returns. It is the most important ultimate goal of the 
forester to bring his forest property to a sustained yield so as to produce a 
nearly equal annual or periodic return. It is only by systematic regulation 
that permanent economic production can be secured. This principle of 
sustained yield is of importance to the individual and to the nation. It is 
customary for the private owner to require equalized returns on his invest- 
ments and the wood industry of the nation also requires fairly sustained 
annual production in order to keep wood-using industries in full operation. 
Serious depression, when industrial production is curtailed, may warrant a 
corresponding diminution of output from public and private forests. On the 



* It is important to differentiate clearly between forest economics, forest economy, 
forest finance, forest management, forest mensuration and forest regulation. 

Forest Economics {syn. Forest Policy). A comprehensive term including all matter 
referring to the position of forests in public affairs. 

Forest Economy. A comprehensive term including all matter dealing with the busi- 
ness aspects of forest management. (See also Fernow, B. F., Economics of Forestry, 
p. 103, 5th edition, New York.) 

Forest Finance. That branch of the science of forestry which relates to the forest as 
an investment. It includes two distinct subjects. Forest Valuation and Forest Statics; 
the first concerning valuations of soil and growing stock, increment, and damage; the 
second with a comparison of the financial results of different methods of treatment and 
other questions of profitableness and financial effects. 

Forest Management. The practice of the application of forestry in the conduct of the 
forest business. 

Forest Mensuration. That branch of forestry which deals with the determination of 
the volume of stands, trees, logs and other timber products, and v/ith the study of 
growth and yield of trees and stands. 



2 American Forest Regulation 

other hand, in times of stress, as was evidenced in France during the War, 
a nation is fully justified in over-cutting its public and private forests for 
the good of the state. 

Of the technical factors which lead to an assured annual yield, the most 
important is the age of the different stands. For it is evident that if all the 
timber in a forest is immature, there can be no production of sawtimber until 
these individual stands ripen. If, however, all the timber is mature, the 
problem of securing a continuous yield of sawtimber may be assured, pro- 
vided the owner is willing to make certain sacrifices, often obligatory when 
part of the decadent and overmature timber is held without cutting for long 
periods. 

Russell and Roth (see § 12) have pointed out the hiatus in national timber 
production which is sure to follow our present era of destructive lumbering. 
Our national timber resources are largely composed of virgin stands* of 
mature and decadent timber and of idle cut-over land, much of it barren or only 
partially stocked, with valuable species; aside from woodlots there is but 
little forest land today in the United States stocked with middle-aged timber; 
therefore it is easy to visualize what will happen when our virgin stands 
are destroyed ; the nation surely will be confronted with a shortage of timber 
land stocked with merchantable timber. Our publicly owned forests will 
be insufficient in area to supply national demands. Even if we wake up to 
the need for permanent forest production before all our virgin timber is gone, 
we cannot now repair the damage in time to avert a serious shortage, because 
it takes from 60 to 120 years or more (see chapter IV-V) to produce sazv- 
timber as contrasted with conkvood. Even if every acre of potential forest 
land were fully stocked with valuable immature timber, when the last of the 
virgin stands disappears, many sawmills must shut down until these areas 
of immature trees ripen. A¥e would be in much the same situation that 
England was when the demand for ammunition overran the supply. Fac- 
tories capable of enormous production were being built but had not yet 
reached the production stage. Fortunately, in the industrial world such a 
shortage can soon be relieved, but in forest management we must face 
squarely the hiatus in production sure to occur if there are no middle-aged 
stands ready to grow into merchantable timber that is certain to be required 
by our rapidly increasing population. 

The owner of merchantable timber when deciding upon the proper cutting 
policy to adopt has three alternatives : 

• (i) In anticipation of higher prices due to the predicted timber shortage 
he may carry his timber as a speculation ; 

(2) He may rapidly convert his stumpage into money and realize on his 
forest investment. High taxes and heavy carrying costs on forest and plant 
investments have induced practically all American lumbermen to follow this 
course ; or, 

(3) He can make a compromise between (i) or (2) ; but after the owner 



* Of course virgin stands contain young and middle aged timber but this is usually 
all destroyed by "destructive lumbering." 



Introduction to Forest Regulation 3 

has decided not to hold his timber as an investment against higher prices 
or to realize on his forest, there is still the important decision, hozv much to 
cut and when. This question must be answered by applied regulation, which 
should always aim at a sustained yield of timber and permanent production. 
It goes without saying, as Dr. Fernow has emphasized in his Introductory 
Note, that regulation cannot be successful without sound silviculture, nor 
are the two incompatible. Rc-grozvth, ordinarily by natural regeneration, will 
always remain the sine qua non of successful forest management in the United 
States. 

2. Conception of Regulation in Europe. It is instructive to see what the 
European idea of regulation is in the exact words of great foresters. Huffel,* 
the foremost French authority says : "The management (or regulation) of 
a forest includes all operations which aim at systematizing the cut." He 
argues that public forest owners have only the right to income from properties 
and must pass the principal on to the future generations unimpaired ; that 
this is the fundamental idea of forest regulation. He admits, however, that 
the private owner should be given more freedom in the use of his property 
according to his individual needs. All owners are, however, benefited by 
systematic forest working plans, "which indicate for a definite period, (i) 
the date, (2) the method, (3) the location, (4) the extent (degree) of all 
fellings which will be made in the forest." 

The German and Austrian definitions** emphasize profit, orderliness and 
continued yield: Judeich (Saxony) says: 

"The object of forest management is the most profitable use of soil or 

land for. raising timber The task of regulation is to order in time 

and place the entire management or business of the forest, in such a manner 
that the object of the management is accomplished as fully as possible." 

According to Martin (Prussia and Saxony) forest regulation, 

"comprises the measures necessary to conduct an orderly forest manage- 
ment Regulation forms the most important subject of instruction 

in the business of management of the forest The most important 

task of regulation is to direct the order or progress of the harvest or cut and 

removal of the several stands of timber The most difficult and yet 

the most important task in the preliminary work is a suitable division of 
the forest into permanent sub-divisions." 

Von Guttenberg (Austria) defines regulation as, 

"that part of the science of forestry (and particularly of forest management) 
which attempts a well planned order and arrangement of the entire manage- 
ment of a forest, and especially the regulation of the cut in order to assure 
the most profitable and sustained yield or income from the property." 

Stoetzer (Saxony) also bears on the sustained yield idea and adds other 
details to his definition of what regulation is: 



* Huffel, G., Economic Forestiere, Tome Troisieme, 1907, pp. 4, 7, 8, 12. 
** Adapted from the appendix of F. Roth's Forest Regulation, pp. 203-218. 



4 AincricaJi forest Regulation 

" It maintains order in the management of a forest; it regulates 

particularly the manner and time of cutting ; it plans to restock the 

land with new stands of trees, and it determines the amount of timber which 
may be cut each year without diminishing the wood capital or endangering 

the continuance of such a cut for the future The provisions of forest 

regulation are not employed for individual stands of timber, cut at intervals 
of many years, but apply to forests where a yearly cut of timber is possible 
and is demanded." 

3, Scope of Regulation. As a matter of fact, the correct regulation of 
cut on a forest requires a complete and detailed study of all local and general 
conditions. Regulation depends on correct answers to the economic, business 
and technical problems presented. It is most intimately linked with (a) 
Stock taking and growth, included in mensuration (Business group), (b) 
Policy and history (Economics), (c) Forest finance (Business), and (d) Sil- 
viculture, protection and lumbering (Technical). But the more the following 
diagram (after Chapman, page 4, Forest Mensuration, John Wiley & Sons) 
is studied, the clearer becomes the interrelation between forest regulation 
and the parts of the physical, mathematical and human groups: 



RELATION OF REGULATION TO OTHER SUBJECTS IN FORESTRY 



Group 



Economics 
Kumua 



"Business 
Mathematical 



Technique 
Physical 



Language 



History 
Economics 





Forest 


Forest 


Economic 


SciCDces 


Forest 




History 



Applied 
Sciences 
Economic 

and 
Technical 



Physics 
Chemistry 



Forest Policy 
and Laws 



Busiaessor 

Orguniyjitloa 




Geology 
Botany 
Zoology 
Mcchanfcs 



Forest Physiography 
Dendrology 
Forest Ecology 
Porest Entomology 
Wood Technology 



Silviculture 
Forest Engineering 
Lumbering 

Wood Using Industries 
Forest Protection 



Fig. 1. 



4. Land Classification, an Initial Step. As our industrial development 
continues, land originally classified as chiefly valuable for forest production 
may eventually be devoted to other uses. But before regulation can be 
intelligently planned, it is obviously necessary that the land classification 
must clearly differentiate for the time being between agricultural and forest 
soils. If the estimate of permanent production is based partly on stands 
growing on agricultural land soon to be cleared, the whole arrangement will 



Infroduction to Forest Regulation 5 

be disrupted if this land must be withdrawn from the forest for purely 
agricultural uses. 

5. Details Must be Systematized in Working Plans. Forest Regulation or 
Forest Organization is therefore the systematic and orderly presentation of 
the business* of Forest Management usually embodied in a formal luorking 
plan which is : 

The plan or plans under which a given forest property is to be continuously 
managed. Annual or periodic plans may be based on the general working plan 
and may refer to any specified class of zvork, as the annual cutting, pla^tting^ 
protection, grazing, or administration and improvement plan. 

Such annual plans may be either mere 'schedules or may contain more or less 
detail, explanations, estimates of cost and results, as seems desirable. 

Details of forest management must be systematized to avoid waste. The 
past and the future policy upon which forest management is based must be 
clearly presented to the manager and the basic local economic data** con- 
cerning the area must be collected so the forest can be divided to suit the 
system of silviculture and intensiveness of treatment. Then the essential 
regulation of cut — the soul of forest regulation — can be determined and the 
time to cut each compartment decided upon. In American forest regulation 
silviculture zvill usually take precedence over the mere dictates of forest mathe- 
matics, but the two of course should be correlated. 

Without system, the work of one manager is lost to his successor. The 
manager who "carries the data in his head" is the forester of the past gener- 
ation ; he is the sort of man who is eliminated by the modern board of 
directors who insist on constructive business efficiency. 

6. Progress of American Regulation in Early Working Plans. The prog- 
ress of Forest Regulation in a country is a sure indication of the intensiveness 
of forest administration. Every annual report in British India catalogues 
the area under working plans, because this is considered a criterion of advance- 
ment. But in the United States, curiously enough, while the initial work of 
trained foresters was early centered in the preparation and publication of 
working plans for private timber lands, yet today there are few plans for 
public forests, although the regulation ideal has never been lost sight of. 
But judging from the interest in management that has arisen during the past 
year (see appendix E), the present lack of really effective National Forest 
plans will soon be remedied. 

The earliest published plan*** set the standard for private working plans and origi- 
nated diameter limit methods* of regulating the cut which were blindly followed in other 
plans without regard to type, or character of cutting and silviculture. A method which 
might give passable temporary results in the tolerant spruce forests of the Adirondacks 



♦Chapman, H. H., Working Plans (P. S. A. F., Vol. X, pp. 376-383, 1915). 

** Chapman, H. H., Forest Mensuration, John Wiley & Sons, New York, 1921. 

*** Graves, H. S., Practical Forestry in the Adirondacks (Bureau of Forestry Bulletin, 
1899). 

* Moore, Barrington. Working Plans: Past History, Present Situation, and Future 
Development. (P. S. A. F., Vol. X, pp. 217-259.) 



6 American Forest Regulation 

naturally failed when applied without modification to almost clear cutting in the 
intolerant pineries of the South. 
According to Olmstead,* 

"The yield to be expected from cutover lands shows a high return from the capital 
invested in them .... cutting to ... . twelve inches breast high (fourteen inches 
stump) .... with stumpage at two dollars (now one fifty), land at one dollar per 
acre .... the annual interest represented by the future crop on cutover lands for a 
period of forty years, is nearly nine per cent .... The lands which have been cut 
over will be producing timber, which at a conservative estimate represents an income 
of 8.8% on the capital invested in them." 

This calculation applies to short-leaf and loblolly pines in the South, but Fernow** 
says, "The real interest which the above quoted example will give is about 5/^%. 
This is considerably different from 9%." 

The reason why working plans for private lands were so important a part of the 
work of tlie Bureau of Forestry (prior to the establishment of the Forest Service on 
February i, 1905) was that these were but a means to an end — a useful method for 
advertising forestry, a propaganda which proved entirely successful in enabling a 
technical bureau to assume charge of the National Forests (then termed Forest 
Reserves). The technical failures of these early plans according to one writer,*** were 
due to putting future interests ahead of the present, a failure to understand that the 
lumberman's wanton destruction of forests was dictated by economic factors; this 
latter shortcoming was because they had not received a proper business training. 
These plans attempted the impossible and copied too closely the European counterpart. 
Where less was attempted, a greater measure of success was secured.* This early 
activity in working plans was under the artificial stimulus of a propaganda campaign. 
A measure of technical success it is true was attained in the woodlot plans because here 
the main emphasis was placed on silviculture (and especially on the immediate execu- 
tion of sample thinnings) rather than on regulation. 

7. Stock Taking by the Forest Service Preliminary to Regulation. When 
on February i, 1905 the Bureau of Forestry was given the National Forests 
to administer, the problems of organization, fire protection, grazing, improve- 
ment and the sale of timber occupied the attention of those in charge. 
Sporadic attempts w^ere made to draw up prelitninary working plans but the 
main expenditures during the next decade were on mapping and estimating. 
These data were for timber sales and for rough purposes of regulation — to 
prevent overcutting. Generally speaking these early estimates have proved 
too inaccurate for the modern timber sale appraisal unless corrected by com- 
paring them with the results of cutting in timber sales — and even then the 
results are not wholly satisfactory. All of the rough estimating eventually 
will have to be done over again. This was to be expected and it can safely 
be said that as a policy a rough estimate for every forest was entirely proper 
because it cost perhaps but a cent or two an acre. As a result of normal 
economic development more accurate estimates will be justified later on. 
Forest history certainly justifies the rough timber survey of a forest area as 



* Olmstead. F. E., "Working Plan for Forest Land Near Pine Blufif, Ark." (Bureau 
of Forestry, Bulletin 32, 1902, page 44.) 

** Fernow, B. E. (Forestry Quarter!}-, Vol. i, page 32, note). 
*** Ibid., pp. 221-222. 

* Foley, John. Conservative Lumbering at Sewanee, Tennessee. (Bureau of 
Forestry, Bulletin 39, 1903.) 



Introduction to Forest Regulation 7 

an initial step in regulation. Only high stumpage prices and intensive 
markets justify costly and intensive estimates. Preliminary regulation 
requires not only a knowledge of the resources but equally important, sys- 
tematic data on the marketing, manufacture, and utilization of the product 
and basic information on silvicultural practice. During this initial period 
of development no satisfactory or practical regulation scheme was developed, 
notwithstanding a number of attempts. According to the 1919 Forest Service 
Manual (Reg. S-2), the limitation of cut is now as follows: 

"The Secretary of Agriculture will prescribe from time to time, upon data furnished 
by the Forester, the maximum amount of matured and large-growth timber which may 
be cut by years or other periods, on each National Forest or other unit." 

In many countries the annual cut is fixed by the Secretary (the ranking ofificial) since 
the technical services in principle should not establish the allowed cut for the forests 
they supervise. Probably more effective results would be obtained in the United States 
if the limitation of cut on National Forests were checked and correlated by an inde- 
pendent forestry advisor actually serving in the office of the Secretary of Agriculture. At 
present the limitation of cut figures are prepared by the Forest Service and the Secre- 
tary's approval is purely perfunctory. But such a plan of re-organization will probably 
not be adopted because of the additional cost. 

Today efforts are continued to systematize estimating and mapping, since accurate 
regulation of cut as a vital problem by itself can only follow reliable estimating which 
in turn is dependent on appropriations; until very recently estimating on National 
Forests was frankly based chiefly on timber sales demands but now the policy has been 
changed so as to give more emphasis to obligatory regulation. 

8. Regulation on Privately Owned Property. Strictly speaking, there has 
been no regulation on private, state, or institutional lands. 

On the Vanderbilt property near Asheville (now Pisgah National Forest and Game 
Preserve) silviculture dominated the early cutting policy, but today the forest is being 
heavily culled prior to its being turned over to the United States. On the Whitney and 
Webb tracts in the Adirondacks the regulation of cut has been made subservient to a 
good business showing. Yale has managed the forest property of the New Haven 
Water Company,* but systematic regulation has not been commenced because good 
silviculture demanded the removal of diseased chestnuts, and a formal working plan 
has thus far been deemed unnecessary. Improvement thinnings and planting rather 
than regulation was what the forest needed. Similar conditions have dictated the policy 
at Sewanee, Tennessee and at Syracuse, N. Y. (State College of Forestry), where 
important school forests are being successfully managed. Of college forests the 
Harvard Forest alone has been really regulated during the past ten years. 

Silviculture must come first, to be sure, but during the initial period, it 
appears only too easy, even for technical forest schools, to minimize the 
need for systematic mandatory regulation. It is predicted that regulation 
will come into increasing prominence during the next decade. For without 
a systematic attempt to regulate the forest for continuous production in 
accordance with correct silviculture, forest management cannot be put into 
effect. 

9. Quiz. What is the distinction between forest regulation and forest finance? 
forest mensuration? 



Hawley, R. C, Bulletin 3, Yale School of Forestry, 1913. 



American Forest Regulation 

What are the essentials of a definition of regulation? 

In what particulars do different autiiors vary in their definitions of regulation? 

Why were working plans made for private timber lands prior to 1905? 

How was forestry benefited by this? 

Why did these plans fail technically? 

Why were calculations of profit too high? 

Why are working plans now being developed for National Forests? 

Why were rough timber surveys justified? 

What restrictions as to timber sales are now made by the Forest Service? 

Which should come first, silviculture or regulation; should the two be correlated? 

What replaces regulation on privately owned forests and why? 



CHAPTER II 

BACKGROUND OF A REGULATION POLICY 
AND SUSTAINED YIELD 

10. Basic Conditions. Gifford Pinchot, in an address delivered in 1921, 
declared that the United States must have a National forest policy for the 
conservation and regulation of forests. More than half of our original timber 
has been cut and burned away. We are cutting what remains more than 
four times faster than it is being reproduced. Three-fourths of what we 
have now will be cut within twenty-five years. When our own timber is 
exhausted, neither in Canada nor in Mexico nor elsewhere in all the world 
can we get the kinds and quantities of timber that we need. The supply 
of timber indispensably necessary to keep our agriculture, mining, manu- 
facture and transportation productive and prosperous is the greatest and 
most far reaching economic question now before the people of the United 
States. 

One-fifth of the timber of the United States is in State and National Forests 
(almost wholly in the latter). Four-fifths is in private hands, and is being 
destroyed as rapidly as ever. If we are to mitigate or escape the timber 
famine which is now clearly ahead, forest devastation on the privately owned 
commercial timberland must stop. Already more than eighty million acres 
of forest lands in America have been so completely devastated that they 
produce nothing, and the lumbermen are extending this devastation every 
year over a total of new land as large as the whole State of Connecticut. 

A National forest policy, to be effective, must put a stop to forest devasta- 
tion, control or prevent forest fires, and provide for raising at home the 
timber without which the United States cannot even exist as an organized 
community, to say nothing of the safety, prosperity and comfort of our people. 

The forest policy of the United States, Mr. Pinchot points out, must be 
nation-wide for many reasons. Already more than three-fourths of our 
people live in the states whose forests are unable to supply their own needs 
for lumber. All of our greatest agricultural and industrial communities are 
in the thirty-three timber-importing states. The timber-importing states are 
rapidly increasing in number and the timber exporting states rapidly dimin- 
ishing. The timber-importing states contain four-fifths of our agricultural 
values, and nine-tenths of our manufactures are produced in them. Seventy 
per cent of the lumber used in America is consumed outside the state in 
which it is cut. Half of the timber left in the United States is in the three 
states of Washington, Oregon, and California, which contain but five per 
cent of our population. How to get lumber is a far more pressing problem 
for the states which do not have it than for the states which do. It takes 
more wood used in more ways to feed, clothe, and house the city dweller 
than the farmer or the mountaineer — the people far from the forest than those 
who live in or near it. The only way to prevent control of lumbering on 



lo American Forest Regulation 

privately owned timberlands from imposing unfair and unequal burdens is 
to make it National and, therefore, uniform throughout the Nation. The 
only control that can be impartially enforced is National control. The only 
control that can be kept free from politics is National control. National 
control can be adapted to local conditions fully as well as state control. The 
only organization prepared to enforce control, with full knowledge, long 
experience, and undisputed character and ability, is the United States Forest 
Service, which has been doing with marked success in the National Forests 
almost exactly what National control would have it do on commercial timber- 
lands. National control through the power to tax is simple, easy of enforce- 
ment, and in accordance with our way of doing things, and would require 
little or no machinery beyond that already in existence. So run the facts 
and arguments in Mr. Pinchot's address.* 

11. Basic Studies. Since forest lands cover one-fourth the area of the 
United States, their development and use will become increasingly important 
as this shortage of forest products develops. This development and use will 
depend: (i) On the policy of the owner; (2) on the economic conditions that 
affect values; (3) on the exact silvical knowledge available. This third con- 
dition is fundamental, because policy and values are so closely linked with 
thorough knowledge of growth and silviculture. The study of volumes and 
growth are important branches of forest research, but all research, directly 
or indirectly, aims at the solution of the problems underlying forest regu- 
lation. To be sure, there must be a balance between policy, economic con- 
ditions, and the results of research ; but research is often so all important a 
problem that it may come first. At present there is a tendency to give eco- 
nomics too much prominence. Shall timber sales sway absolutely forest 
regulation? Or will regulation influence the business of lumbering? This 
general question must be decided in each case on its merits, but the true 
ideal of forestry is unquestionably to put sound regulation (based on research) 
first. 

12. Curtailment of Production. Recent attempts to curtail normal govern- 
ment timber sales on the Pacific Coast so as to relieve the private owner of 
competition, are needless and unwise; and yet recently a forester proposed 
that the regulation of the private timber resources in the South to prevent 
too rapid exhaustion might demand assigning a cut to that region with the 



* An interesting- proposal is made by Roth and enlarged upon by Watson (J. of F., 
Dec, 1921, pp. 817-835, "Sustained Annual Yield as a National Policy of Forestry") to 
organize and plan for forests cut by any accepted method, but to protect the actual 
growing stock by allowing only the cutting of one-third the basal area per forty acres 
every twenty years. This would certainly tend to stop forest devastation and would 
prolong the cut but like rigid diameter limit systems is too artificial to be generally 
applied throughout the country to all types of stand. Watson is, however, on the right 
track when he states (in the article cited above) that: "It has been shown in the pre- 
vious pages that neither satisfactory fire protection, silviculture, nor a system of taxation 
of private lands can well be established until the forest properties of the United States, 
private as well as Federal or State, are brought under a form of continuous forest 
production .... some form of forest regulation is needed .... in a mandatory 
fashion." 



Regulation Policy and Sustained Yield 1 1 

object of forcing some owners there not to cut more than a certain amount. 
This amount could be gauged by the potential productivity of the soil, and 
would be dictated by the future danger of a timber shortage. This is a bold 
plan, but indicates how regulation may sway the economic problem of pro- 
duction. With the laying waste of forest lands owing to overcutting, such 
as has taken place in the Lake States, how long will it be before soil values 
can be restored? Unquestionably it will be years, and the expense will be 
many times the cost of cutting more conservatively in the beginning. This 
truism is fundamental of good forestry. 

Watson* figures the possible annual growth from all timber lands in the 
United States at about the amount now used, but before the possible annual 
growth can be secured, from fifty to a hundred years must elapse. In other 
words, past overcutting means a hiatus in our national sustained yield (see § i). 

13. Continuous Forest Production. In a broad sense the policy of holding 
timber lands on the basis of continuous forest production means: (i) Stabil- 
izing the lumber industry, (2) the adoption of a true and sound forest policy, 

(3) a solution of important land and forest labor problems of the country; 

(4) provision for permanent cheap transportation in the forest. As soon as 
timber lands, both public and private, can be placed on the basis of permanent 
forest production, the greatest advance will have been made in national 
conservation — the first step towards the termination of forest destruction. 

14. Early Western Land Policy and Its Results. Conditions in the West** 
during the past half century have led away from systematic regulation rather 
than towards it. ' First the Government tried to dispose of its land for revenue 
and railroad development ; then for the benefit of settlers, and throughout 
the application of the public land policy, there were always frauds which 
involve astounding values in public property. In the West, too, frequently 
the citizen endeavored to beat the United States, and to see how he could 
get around the law. The laws, themselves often impractical, encouraged 
this viewpoint, and there was unbridled exploitation of resources with no 
regard for the future; (a) in agriculture (where the soil was "cropped"); 
(b) in land speculation; (c) in forest devastation; (d) in extravagant methods 
of mining; (e) in illegal fencing; (f) in the free disposal of water-power 
and water-power sites; (g) in survey frauds; (h) in swamp-land frauds; 
(i) in the profligate disposal of railroad land grants; (j) in homestead com- 
mutation. 

The Public Lands Commission reported: 

"Detailed study of the practical operation of the present land laws, particularly of 
the desert land and commutation clause of the Homestead Act, shows that their 
tendency far too often is to bring about land monopoly rather than to multiply small 
holdings by actual settlers .... The settler is at a marked disadvantage in com- 
parison with the shrewd business man who aims to acquire large properties. There 
has been spoliation and illegality due to the weakness in laws, speculation and corrup- 
tion of petty officials appointed for political reasons." 



* Russell Watson (J. of F., 1921, pp. 390-393). 

** Hill, Robert Tudor, "The Public Domain and Democracy" (Columbia University, 
1910). 



12 American forest Regulation 

According to Hill,* "The situation seems partially to reduce itself to this: 

(i) Exploitation of natural resources has produced waste, and future social interests 
have been disregarded. 

(2) Frauds against individuals and society at large represented by the Government, 
have been encouraged and perpetrated on a large scale, and private and public 
dishonesty has ensued. 

(3) Public estate has been used for private interest on a large scale. It takes time 
for social ideals to change. Social disapproval has been extended far enough to pre- 
vent the individual from holding himself superior to law." The paragraph numbers 
have been inserted to give force to Mr. Hill's conclusions. 

Thus, as a background to forest regulation in the West, we have the doctrine 
of individual liberty, the opening of the public domain to give away the 
natural resources which were fast disappearing. 

One of the** troubles with the early western administration, was that 
business principles were needed just as if the public domain were a private 
estate. When an efficient administration of the National Forests was com- 
menced, misunderstandings of policy and objections to the rules and regula- 
tions were prevalent. The mining interests were afraid that they were going 
to be unable to proceed unmolested and unrestrained, and that they would 
not get timber at a reasonable cost. The grazing interests were afraid that 
restricted grazing would mean confiscation of their stock, and before the 
repeal of the lieu land-selection law, all the public feared that the large owners 
would denude their land and then exchange it for script. Such objections, 
which were most potent in northern California, found some vent in other 
parts of the West.*** These fears have been disproven. 

15. Effect of Economic Lumbering on Forest Management. A study* 
of the lumber industry by the Forest Service has shown clearly that 

"forest conservation is affected by economic conditions in manufactures whose raw 
material is wood. Demoralized lumber markets affect the value of timber, the stability 
of its ownership, the degree to which it is wasted in exploitation, and the possibility 
of carrying out any far-sighted plan of forest renewals," the need for broad gauge 
regulation is all the more important. 

According to Greeley, ". . . . the main problem of the lumber industry is a forest 
problem. It is a problem which has grown out of quantities of cheap timber acquired 
from the public domain." 

Greeley shows that the West has a surplus of saw-mills and logging camps, 
that there has been speculation in timber, that owners have over invested, 
that mill capacity has been excessive, and there have been poor methods of 
finance, and low efficiency in manufacture and in salesmanship; that com- 
petition has been destructive. And yet unquestionably, as Greeley shows, 
"the public is vitally interested in the prosperity of the lumber industry in 



* Ibid., page 215. 

** Woodruff, G. W., "The Disposal of Public Lands." (Proceedings S.A.F., March 
ID, 1904, page 53-) 

*** Potter, Albert F. "Objections to the Forest Reserves in Northern California" 
(P. S. A. F. Vol. I, 1904, page 50). 

* Greeley, W. B. "Some Public and Economic Aspects of the Lumber Industry" 
(part I, Secretary of Agriculture, Report No. 114. 1917). 



Regulation Policy and Sustained Yield 13 

regions where it is the dominant factor in the economic life of the com- 
munity." Unquestionably there is need for 

"a more suitable kind of forest ownership .... the extension of public forest 

ownership is needed. Private ownership has shown itself ill fitted to the task 

.... private cooperation in taxation and fire-protection .... reasonable public 
regulation of the handling of private lands will unquestionably find a place in working 
out the problem." 

The conclusions are that within the next two decades there will be local 
timber shortage, hastened by over-production due to the wrong kind of 
ownership. The answer to all these evils which Greeley has enumerated in 
his study of the lumber industry is unquestionably broad gauge forest regu- 
lation, which primarily must be based upon the study of growth because, as 
already emphasized, without knowledge of the rapidity of timber production 
per acre, the regulator of forests has little chance of giving correct answers 
to the various problems. 

The public must cooperate with the private owner to make a regulation of 
cut a practical business. There are people today who fear regulation of cut 
and the curtailment of lumbering operations and the consequent restriction 
of local development. We have simply reached another stage in the manage- 
ment of our national forest wealth, — the obligatory regulation stage, — and 
this does necessitate some present day sacrifices for increased future benefits. 

According to an unpublished paper by Zon, 

"Another persistent fallacy is that forestry cannot be profitably practiced unless 
stumpage prices are high enough to raise timber to maturity on a bare tract at a profit 
above all costs including compound interest. If we are to allow our forests to be 
turned into deserts and then expect to reclaim them by planting, the chances for having 
in this country any forests at all, are very slim indeed." 

If forests are completely wrecked, it will take a century or so to repair the 
loss. According to present estimates, private owners have fifty to sixty 
years of supply at the present rate of cutting. There is an annual demand 
of approximately one hundred billion feet a year, forty billion for lumber, 
and sixty billion for ties, poles, fuel, and fencing. To supply such an enor- 
mous demand there is need of young age classes to grow the forests of the 
future. According to Zon, 

"If all our forests were placed at once on a sustained yield basis, they 
would absolutely produce the annual supply of wood needed in this country." 

But today the lumberman is afraid of regulation. Under present condi- 
tions there has been over investment by the lumber industry. Owing to the 
high cost of capital, the incentive to destroy the forest investment as soon as 
possible in order to reduce the carrying charges has predominated. 

16. Possible Solutions; Restricted Private Control, or Public Ownership? 
There are two possible solutions to this problem ; control of thcprivate indi- 
vidual, and restriction as to how he shall use his forests, or, ownership by 
the public. Because of American Democracy the viewpoint that the public 
must own most of the forests, is, in many ways, logical, but a large proportion 
will of necessity remain in the hands of the individual. Tourney* says. 



Touniey, J. \V., Who shall Own the Forests (Yale Review, Oct., 1913, p. 156). 



14 



American Forest Regulation 



"Can you look forward to the time when at least one-half of our permanent forest 
area will be publicly owned? If not, our private forests must come under governmental 
control, with prescribed methods of management. Future development in American 
forestry must be in one or the other of these directions. The writer believes public 
ownership is far more in harmony with American instincts, and more acceptable to the 
great body of American people." 

If the private owner, notwithstanding carrying charges imposed by taxa- 
tion and interest on his investment, desires to own forest land, and yet 
refuses to adopt conservative methods of treatment, what is the solution? 
With a situation such as this, an ex-appropriation of at least those forests 
which cover erodable slopes and water-sheds will unquestionably be forced 
in the interests of the public. For forests in level country, that are merely 
supply forests, perhaps conservation has not advanced far enough in this 
country to justify at once federal or state control. Time will tell. Fernow* 
in discussing the control of small owners says: 

"The former may be largely left to the free exercise of private enterprise, and this 
will probably be the answer to the regulation problem so far as it touches the small 
owner; he will not brook control, and so long as he is willing to fight it, probably he 
will have his own way." 

Kirkland** argues that public ownership is not necessary even to secure 
a sustained annual yield ; that it would be practicable to put the forest 
industry on a permanent producing basis by establishing a central association 
of American forest industries which should classify, finance, organize, and 
standardize the business of the members, and most important of all regulate 
output and prices. 

"The only effective maintenance of price must be one through limitation of the 
quantity placed on the market. The only sound limitation of the amount to be 
marketed annually is that imposed by what this resource will produce continuously. 
Bad as that forestry is which overcuts any given producing unit, that which undercuts 
is still worse because it neither furnishes revenue to the owner nor supplies the 
consumer with product." 

Fernow for one does not believe in the practicability of Kirkland's plan 
nor does the writer, unless this suggested association of private forest owners 
is under National control — an association of private owners and producers 
under the guidance of the Forest Service would undoubtedly work efficiently 
and may be the solution of preventing the present devastation. 

17. Policy and Definition of Sustained Yield. Granting that there must 
be public control of forests, we have then to answer the question. Shall the 
cut be according to the principle of a sustained yield or shall economic con- 
ditions and fiscal expediency gain the ascendency in the decision as to "How 
much must be cut"? 

Sustained yield is the yield or cut of timber from a forest zvJiich is managed 



* Fernow, B. E., Economics of Forestry, New York (5th Edition, p. 271). 

** Kirkland, Bert T., Continuous Forest Production of Privately Owned Timberlands 
as a solution of the Economic Difficulties of the Lumber Industry. (Journal of 
Forestry, Vol. XV, 1917, pp. 15-64.) 



Regulation Policy and Sustained Yield 15 

in such a zvay as to permit the removal of an approximately equal volume of timber 
annually or periodically. 

It is argued* that a sustained annual yield gives the best social results, the 
best investment, the safest management. In Europe there can be no question 
but that forest workers, with permanent work in their local valleys, are 
better ofi' than they are in temporary logging camps of the United States. 

18, Comparison with Conditions in France. According to Huffel, the foremost 
Frencli authority,** the arguments in favor of an annual yield are summarized as follows: 
most wood products will not stand long distance transportation so that it is better to 
cater to local markets which are often dependent upon an annual wood supply for their 
prosperity; a sustained cut is better for lumberjacks and teamsters as well as for wood 
using industries; an annual revenue is best for the owner of forests; it is of less 
moment to the state but a necessity for many communes and individuals. This annual 
yield should not be too unequal because of the drawbacks to labor and local industries 
dependent upon a supply of wood. For this reason and on account of the dictates of 
good silviculture, increases or decreases in growing stock should be gradual. But the 
divergence between the intensive forests of France, for example, and the working circle 
of the Pacific Coast is so great that it is very confusing. In the one case (France) 
the working plan may regulate a working circle of but a few thousand acres; in the 
other case perhaps it takes two hundred thousand acres or more to form a circle that 
will yield a large enough cut to justify the maintenance of the local timber-using mills 
and industries. In France, for example, the valley is tributary to a small group of saw 
mills; here the unit of sustained yield is smaller, simply because of its more advanced 
state of forest development, and because of the local labor and market conditions which 
demand an annual cut, and an annual cut convenient to the homes of the workers. 
One does not find in France the large scale railroad logging of the United States. 
Wagon roads permit easy hauling at any point; each little hamlet has its constant 
annual wood and timber needs; the social and economic conditions are absolutely 
diflFerent, and therefore working plans and regulation in the two countries must be built 
on diflferent lines. Often the principles are the same, but the application of methods 
in the Western United States must be broader, and must be changed to conform with 
the different problems that are to be solved. Perhaps in some localities on National 
Forests fire protection must come first, and strict regulation of timber must be retarded 
for another decade or two. Perhaps for a time the pressure for timber sales may 
lead forest administrators to adopt a policy of giving precedence to timber sales exami- 
nations over areas which should be cruised for management reasons; whether due to 
low appropriations or not, this is unfortunate and is now being modified on some 
National Forests; but under existing conditions may for a short time continue to be 
a necessary economic result. Without permanent efficient transportation owned by 
the forest proprietor the present temporary large scale logging camp, uprooted when 
the locality is cut, is a natural consequence of economic conditions. The forest workers 
must suffer; the social evils attendant to a shifting population are proverbial; what 
is more famiiiar than the- wastage and extravagance after a winter's work in the woods! 
Yet in the Eastern United States after two centuries of logging these conditions still 
exist because large scale logging is so customary. With permanent sawmill industries 
and local workers (with families) different social conditions would come logically and 
naturally as in Europe. 

19. Financial Aspect of a Sustained Yield. Usually investments yield 
semi-annual or quarterly returns and recently attempts have been made to 



* Kirkland, Bert T.. The Need of Working Plans on National Forests and the Policies 
Which Should Be Embodied in Them (P. S. A. F. Vol. X, 1915, pp. 341-371). 
** Huffel, G., already cited, pp. 9-12. 



i6 American Forest Regulation 

popularize monthly dividends. To meet the minimum demand for an annual 
income sustained yield production of forests is necessary. The recent studies 
of the lumber industry* indicate that better financial results (because of over- 
production under existing methods of wrecking the forest property) can be 
brought about only by, 

"A more stable kind of forest ownership, divorced from manufacture to a larger 
degree than now, must come about before the ills of the lumber business can be perma- 
nently cured .... Private ownership has shown itself ill-fitted to the task, at least 
in the larger forest regions." 

Legitimate demands for timber must be met, but forced sales** should be 
discouraged. Then too, it is generally recognized that present methods of 
taxation*** are an incentive to over-production, since the operator must try 
to create a demand for his timber rather than to hold it for permanent pro- 
duction. It is interesting to bear in mind that a 15 per cent tax on the final 
yield of private stands would yield about the same revenue on the Pacific 
Coast, as is at present received by the communities from the 25 per cent 
tax on current production of all timber cut from the National Forests. 

20. Sustained Yield on Public Forests. Even as early as 1905 the govern- 
ment has idealized a sustained yield. In an early working plan* for private 
lands it was argued : 

"The object should be to get a sustained yield from as small an area as possible, 
provided this does not materially interfere with, or increase the cost of present opera- 
tions. The smaller the area the smaller the invested capital and the yearly tax list, 
and in the long run this means the saving of a considerable sum of money." 

The pul)lic naturally expects the National Forests to be models of permanent forest 
production. Why then has not a sustained yield management been adopted? The 
answer** is: 

(i) That there are physical limitations that are now insurmountable owing to inac- 
cessibility and lack of transportation. "*** .... primary transportation must 
precede any kind of forest management." 

(2) Competition with private stumpage more conveniently located would necessitate 
reducing prices below the danger point if national timber sales had to be forced. "A 
sustained annual yield presupposes a sustained market," which is rarely available. 

(3) The National Forests are a great resource which cannot be depreciated or forced 
on a market which is glutted with cheap private stumpage. Yet as is pointed out,*** 
". . . . management with or without the sustained yield principle is totally unrelated 
to the policy followed in pricing stumpage . . . .," according to the appraisal system 
now in force on National Forests. 



* Greeley, W. B., Studies of the Lumber Industry, Part I (U. S. Dept. of Agriculture, 
Report No. 114, igi/. P- 4-5)- 

** Ibid., page 95. 

*** Hutton, G. W. and TIapham, E. E., Forest Ta.xation as a Factor in Forest Manage- 
ment. (P. S. A. F. Volume 13, 1916, pp. 50.) 

* Chapman, C. S., A Working Plan for Forest Lands in Berkley County, S. Car. 
(Bureau of Forestry, Bulletin 1905, p. 50). 

** Greeley, W. B., National Forest Sales on the Pacific Coast (P. S. A. F. Vol. VII, 
pp. 42-50). 

*** Greeley. W. B., Working Plans on National Forests (P. S. A. F. Vol. X/. pp. 
84-85). 



Regulation Policy and Sustained Yield 17 

Moore* argued that sustained yield is not necessary "where the community forming 
the natural market for the timber is not dependent on National Forest material, — that 
is, where material can be brought in from the outside as cheaply as it can be produced 
locally, — .... where there is no local market for the timber, .... and where 
.... the possible annual sustained yield is too small to warrant the building up of 
a community dependent solely on lumbering." 

The writer agrees that during the development stage of forest management 
there will be innumerable instances where a sustained yield (either annual 
or periodic) will be at present out of the question for practical reasons. One 
must bear in mind that after the first few periods there can still be permanent 
production even if a strict sustained yield does not commence until after the 
first improvement fellings have removed the overmature and diseased timber. 
In virgin forests often good silviculture and a theoretical sustained yield 
during the first rotation do not go hand in hand. One reason why there has 
been so much divergence of argument regarding sustained yield is that it 
has been idealized and its practical limitations** not sufficiently appraised. 

21. Sustained Yield Objectives and Difficulties in Practice. The policy of 
the owner and his objective in managing the forest is always the first con- 
sideration in forestry, and will ordinarily determine the whole course of 
unrestricted management. The private owner may put financial returns first. 
The public owner may not desire to manage the forest from a strict dollars 
and cents standpoint, but may wish to preserve the stand, so as to conserve 
an important water supply, or keep the forest as a recreation ground for the 
public. In any event, the forest resource must be maintained in a state of 
maximum and continuous production. Hence the principle of sustained 
yield enters in, because the ideal of management is the maintenance of the 
largest possible continuous yield. A continuous yield is just as important 
in forestry as in any other kind of business. It is more difficult in forestry 
than other forms of business, because of the length of time required for crop 
production. These difficulties necessitate special plans to accomplish a sus- 
tained yield, which can rarely be attained during the initial years of man- 
agement. 

22. Summary of Limitations on a Sustained Yield Policy. In arguing for 
a sustained yield one must not overlook certain limitations ; the principle 
of sustained yield may be correct but it may not be practicable for a number 
of reasons : 

(i) It is fundamental that the land must be chiefly valuable for forest purposes. 
Obviously it would be shortsighted to plan for permanent production on any area, 
without first inquiring whether the soil itself was now chiefly valuable for agriculture. 

(2) Transportation facilities may not permit. If there is poor transportation, this 
may prove a practicable argument towards cutting more than the amount warranted 
on the basis of permanent production, in order to meet large and temporary transpor- 
tation charges incident to the construction of expensive logging railways. Such a 
situation is unfortunate. 

* Moore, Barrington, Methods for Regulating the Cut on National Forests (P. S. A. F., 
Vol. VII, 1912, p. 12). 

** Woolsey, T. S., Jr., Forest Service Silviculture Plans (P. S. A. F., Vol. XI, 1916, 
pp. 1-17. especially pp. 15-16). 



i8 American Forest Regulation 

(3) The market for timber products may be insufficient to utilize the entire amount 
or the quality of timber produced. Perhaps there are accessible and readily salable 
bodies of timber which are being wrecked, in order that the soil may be used for agri- 
culture, which will for the time being, compete with the owner who desires ultimately 
to adopt the sustained yield principle. This condition is typical of extensive forest 
conditions where a final land classification has not been made, and where economic 
conditions governing the sale of forest products are unsettled. 

(4) The silvicultural needs of a forest may necessitate the rapid removal of over- 
mature timber. Perhaps large areas of mature age classes demand the installation of 
mills whose capacity cannot possibly be supplied when once the excess growing stock 
has been reduced to normal. 

(5) The demand for timber products may fluctuate according to the development 
of cities, mines, or other chance local development, with profitable export of only the 
higher grades of lumber. 

(6) Acts of Providence will always exert an influence against the successful adoption 
of a sustained yield. Fire, insect attacks, disease, windfall (and perhaps war) may all 
tend to derange the application of an exact sustained yield. For example, even in well 
regulated forests abroad the variation in the annual yield is considerable. In the 
Forest* of Retz (France) the cut in 1863 was fixed at 987,671 cubic feet; in 1877, 
1,218,055; in 1887, 996,535; in 1896, 1,241,736, and in 1902, 1,014,319- Such variations in 
a regulated forest under intensive economic demand indicates how much greater these 
variations will be under American conditions. 

(7) Of less importance, but withal to be reckoned with, is the personal factor in 
forest administration. From forest history we know that the tendency of administra- 
tions is to overcut or undercut. Some administrators (British India is an example) 
desire to make a good financial showing; consequently, they may be led to cut more 
than the forest produces, unless they are restrained by working plans based on a clear 
knowledge of forest production. Other administrators (as evidenced by France) may 
undercut the forest, sometimes with poor results, because it means the accumulation 
of over-mature timber and consequently increased danger from disease, windfall, and 
insect infestations. Changes in regeneration methods may disarrange for the time 
being the regulated cut. 

(8) One of the greatest obstacles to a sustained yield is the character of the forests 
themselves; the fact that so far the cut has generally been from virgin forests often of 
mixed species, instead of from second growth or grown as even-aged stands free from 
suppression. (See paragraph 108.) 

The sustained yield management ideal is thus something to steer by. It 
is not so unattainable as the normal forest, but nevertheless there are many 
pitfalls before it can be reached. The administrator and student of forest 
production must bear in mind that permanent production is safeguarded by 
frankly acknowledging a sustained yield policy for working circles of reason- 
able proportion. The working plans officer must be enough of an idealist 
to combat the every day arguments of the opportunist administrator, who 
desires to give practicable considerations too great weight when solving the 
vital problem of permanent forest production. 

23. Quiz. What will future forest development depend upon? 
What is an important aim of research? 

Should preference be given regulation aims or tlie dictates of local business require- 
ments? 

Discuss permanent forest production and conservation. 



* Fisher, W. R. (Quarterly Journal of Forestry, 1910, pp. 285-286). 



Regulation Policy and Sustained Yield 19 

Why do past methods of disposing of the public domain in the West make conserva- 
tive management difficult? 

What were early objections to the national forests? 

What is the matter with the lumber industry? 

How can it be improved by regulation? 

What are the solutions of national regulation of timber cutting? 

What does Kirkland suggest? Is it possible? 

Discuss sustained yield and the worker, the investor, the forest, taxation. 

Why cannot a sustained yield management be adapted at once on national forests? 

When is it claimed to be unnecessary? 

Summarize the sustained yield problem — advantages and limitations. 

How exact can an annual sustained yield be: (a) in France? (b) on our national 
forests? 

What are some of the difficulties in the United States? 



CHAPTER III 
MANAGEMENT AND ADMINISTRATIVE SUBDIVISIONS 

24. Definition of and Size of Subdivisions. In order to intelligently sys- 
tematize the location of cuttings at the proper time, and in order to determine 
the area of forest to be cut over and volume of product to be removed the 
land must be suitably subdivided into practicable subdivisions which are 
defined as a larger or smaller part of a forest property segregated with a view 
to making units for purposes of administration, protection, organisation, and 
management. The size of the subdivisions will depend on the intensiveness 
of management and administration. Where the conditions are intensive, as 
in New England woodlots, the size of subdivisions will obviously be much 
smaller than on the Pacific Coast, In New England the cordwood, poles, 
posts, or ties are usually marketed by the owner. This is facilitated by estab- 
lished wagon roads. Thus if desired small tracts can be managed on a 
sustained yield basis under one working plan. On the Pacific Coast the 
conditions are essentially dillferent because railroad marketing of saw logs 
demands a large area of timber so that the annual cut may be sufficient to 
maintain the investment. Still another factor — the progress of silviculture — 
enters into the problem. With virgin forests, management subdivisions will 
always be larger than where silviculture has been intensified. In the initial 
years of management there will be fewer distinctions in methods of cutting 
and in rotations. It stands to reason that the size of administrative sub- 
divisions will vary in like manner. The forest in Europe under the control 
of one man may be limited to 10,000 acres because of the detail incident to 
administration. The typical national forest of the Western United States 
today perhaps averages a third of a million acres and is as efficiently managed 
in a relative sense as is the 10,000 acre tract in Europe. There may be no 
thinnings, but few sales (and these are centralized), and no forestation ; 
instead the manager's time is centered on fire protection, grazing control and 
the broad problems of administration. It is important to grasp clearly the 
differences in the conditions which indicate intensive or extensive subdivi- 
sions, which are of two kinds: (i) Management and (2) Administrative. 

25. Definition of Management Subdivisions. Management subdivisions 
aim at the orderly location of all data on forest resources so that this 
knowledge can be applied to all timber operations within the forest and the 
results recorded so as to preserve an accurate history of past cutting. These 
subdivisions are divided into working groups and working circles for the 
regulation of yield. 

Working group may be defined as an organisation or working plan unit, com- 
prising an aggregate of compartments or stands to be managed under the same 
silvicultural system and rotation. (Syn: working block; working section; 
management class. G., Betriebsklasse. F., Serie D'Exploitation.) 

Working circle may be defined as an economic forest area managed under one 



Management and Aduiinistrative Subdivisions 21 

plan. It may or may not coincide zvith the administrative unit or zvith the working 
group. (Syn : working plan unit, working figure. G., Wirtschaftsganzes.) 

There appears to be more variation in the use of words for working-group and 
working circle than with other terms of current use in regulation. According to 
Schlich,* the working section (corresponding to working-group) is "a number of com- 
partments .... grouped together into cutting series, .... a number of the latter 
form a working section." Moreover, according to the same author, "if a working 
circle" (our working circle) "consists of only one series of age classes, it is identical 
with a working section" (our working group). A working circle (our working 
circle) is, according to Schlich, an "area which is managed under the provisions 
of one and the same working plan." Other terms have also been introduced. 
Recknagel** used in his first edition the term "working figure" for "that unit which is 
to be managed with the idea of a sustained yield." He stated "But in America the 
unit of regulation, the working figure, must be the market unit." To simplify the unit 
of regulation he omits the distinction between working group and working unit. 
Roth*** uses working section for group and does not distinguish working circle as a 
separate term. 




Fig. 2. — Diagrammatic Sketch Map Illustrating the Distinction between Working 
Group and Working Circle (Syn., Working Unit). 



26. Discussion of Management Subdivisions. The distinction between 
working group and working circle is illustrated by Fig. 2. 

Here is represented a central town, with established sawmills and asso- 
ciated industries, surrounded on the south by (A) agricultural land, on the 



* Schlich, Wm., Manual of Forestry, Vol. Ill, 191 1, pp. 273-285. 

** Recknagel, A. B., The Theory and Practice of Working Plans, 1913, p, 20, p. 33. 

*** Roth, Filibert, Forest Regulation (Vol. i, Michigan Manual of Forestry, pp. 1-203). 



22 American Forest Regulation 

west by a pure (E) Englemann spruce forest managed on an eighty-year 
rotation for paper pulp, on the north and north-east by a large watershed 
stocked with (W) western yellow pine, where clear cutting is followed by 
planting on a one hundred and twenty-year rotation. Directly to the north- 
east of the town is a simple (C) coppice of scrub oak managed on a twenty- 
year rotation ; further up on the mountain is a city watershed, held chiefly 
as (P) protection forest with natural regeneration. The rotation here is one 
hundred and fifty years, and the mixed conifer stand is cut over by light 
selection fellings on a cutting cycle of twenty-five years. In the case cited 
the local industries of the (T) town were entirely dependent upon a sustained 
yield from the combined watersheds. Under these circumstances a separate 
working group would be established for each of the four stands (E. C. W. P.) ; 
since these four stands are tributary to this one town, it would be entirely 
practicable to have one working circle include the four working groups. If, 
on the other hand, instead of four different stands with four different systems 
of management and varying rotations, the entire area had consisted of western 
yellow pine with a hundred and twenty-year rotation, followed by clear 
cutting and planting, hiit one working group would have been established, and 
this would have coincided exactly with the working circle ; whereas under 
the conditions cited in Fig. 2, there are four working groups, because of 
varying types, silvicultural system and rotation. A further complication 
might have been introduced had the area (W) been so large that it could 
not have been conveniently handled under one working group. In such a 
case mere size might have dictated the formation of additional groups. It 
is therefore important to bear in mind that the working group is a smaller 
and narrower management (silvicultural) subdivision than the working circle. 
The working group is determined by type, silvicultural system, rotation or 
size, while the working circle would be determined more by transportation, 
market, and business and not by silviculture. Fernow naturally considers 
"working circle" the broader term, judging the aggregation of stands from 
the administrative yield and market point of view, and "working group" the 
narrower term, based mainly on silvicultural management as a unit. 

27. Factors that Justify Formation of Working Groups, The formation 
of separate working groups may thus be dictated by the following factors : 
(i) forest type, (2) silvicultural system, (3) rotation, and (4) size of area. 

(i) Forest type. Types differ according to the kind of product yielded, 
silvicultural system of cutting and reproduction. They may demand a differ- 
ent rotation ; therefore, whenever types cover such a large area or dift'er 
sharply in products yielded, rotation, method of cutting or reproduction, 
that they cannot be worked as one group for the regulation of the yield, it 
is necessary to establish different working groups, 

(2) Silvicultural system. Suppose that on one watershed there is clear 
cutting followed by planting, while on another the forest of yellow pine is 
managed by selection cutting; here separate working groups would be indi- 
cated. If these stands could be managed under the same silvicultural system, 
probably no distinction into two working groups need be made. 



Management and Ad)ninistrative Siihdivisions 23 

(3) Rotation. Where two entirely different rotations are necessary, separ- 
ate working groups must be established. This is not always the case, how- 
ever, because in a mixed stand, frequently species with dift'erent rotations 
are managed under an average rotation in but one working group. But if 
the types were entirely separate with widely varying rotations, then different 
working groups would be essential. 

(4) Size of area. A single working group must have eventually, if it is 
clear cut, a complete series of age classes, and these age classes must be as 
small as is consistent with economy in logging, so as to reduce the danger 
from fire, windfall, fungus and insect damage. It is a fundamental maxim 
of silviculture that large even-aged stands endanger the forest; therefore 
with a very large working group, excessively large age classes could not be 
avoided if a clear cutting system were practised. Consequently, more than 
one working group might be necessary in order to reduce the size of the 
age classes. 

28. Working Circles. The working circle (as contrasted with working 
group) is, in theory at least, dependent chiefly on the market, but under 
modern methods of rail transportation so typical of American lumbering, 
the market may not be the primary factor except in the case of small local 
market units where rail transportation does not enter into the problem. Rail 
markets draw from a wide territory, and therefore a working circle may, 
under exceptional circumstances, be composed of several forests so far as 
the market is concerned, but restricted in size because of administrative or 
management grounds. Ideal conditions for a working circle, where a sus- 
tained yield is desired, consist of a complete market, complete transportation 
facilities of a permanent character, such as drivable streams, or a permanent 
system of forest roads. If temporary roads, railroads, or flumes must be 
built by the operator and paid for by him from the operation of cutting the 
timber, then these apparently unavoidable economic conditions make the 
attempt to regulate the annual cut more perplexing. In some cases it might 
mean that there was not enough timber locally to permit of a sustained 
yield until later rotations, and it must therefore be cut off rapidly in order 
to make a practical logging chance. An economic woods operation would 
be secured at the expense of the sustained yield — an objectionable feature. 

Under extensive conditions such as exist on the Pacific Coast, working circles are 
laid out in territory logically tributary to manufacturing centers by existing or possible 
transportation. This basis, under these conditions, fits in with the objective of a 
permanent industrial center and should have more weight than topographic or adminis- 
trative conditions, which are here of secondary importance. Another problem met with 
under extensive conditions is whether to take into consideration land under private 
ownership when establishing national forest working circles. The policy should 
unquestionably be to give due consideration to the private timber which will probably 
come into the market, since this will help to maintain the industrial center just as 
surely as the cutting of public stumpage. Allowance on the other hand must be made 
for timber land, which may be chiefly valuable for other purposes, since such areas will 
not contribute to the support of the economic working circle after the first crop of 
timber is removed. 



24 American Forest Regulation 

29. Policy of Small or Large Working Circles. Really effective regula- 
tion and a future sustained yield can best be oljtaincd by securing reasonably 
small working circles (working plan units) today. Very large working 
circles, such as have been planned for some of our western forests, will pre- 
clude the possibility of moderate sized local sawmill industries, because if 
virgin stands are cut heavily on a watershed (with the idea of moving opera- 
tions to another watershed of the working circle later on), there will be no 
local merchantable timber for cutting after several decades. Where possible 
the plan ad\ocatcd by Wolff* of having working circles coincide witii natural 
main drainage areas is certainly logical, the intensification of administration, 
the fire danger, the bodies of overmature timber in immediate need of dis- 
posal and the sale of some of the less accessible timber arc problems which 
can be adjusted and overcome. Small working circles will encourage per- 
manent local industries, stable labor conditions, more permanent improve- 
ments, diversification of sales, better silviculture and protection. It is "the 
safe conservative course" ; and the development and maintenance of logging 
communities is certainly desirable. 

30. Definitions of Block, Compartment and Lot. To build up suitable 
working groups and working circles it is convenient to first divide the forest 
area into smaller subdivisions in keeping with the intensiveness or extensive- 
ness of management. The smaller the division, the easier it will be in after 
years to segregate management data according to new and more intensive 
lines made necessary by a change in economic conditions. 

Since forest regulation is the arrangement of operations as to place, time 
and quantity, subdivisions are for the purpose of making convenient and 
possible the location of all operations, as follows : 

(i) On the ground, so that operations can be conveniently conducted in 
the forest. 

(2) In the of^ce, in order that records may be systematized by tabula- 
tions or by means of maps or graphics; these essential records include (a) an 
inventory of estimates and (b) the record of future operations. 

In American forest regulation three subdivisions may be distinguished : 

(i) Block — A major division of the working circle, intermediate in size 
betzveen the zvorking circle and a compartment. A block is usually based on 
topography and comprises a main logging unit or group usually based on topog- 
raphy and comprises a main logging unit or group of logging iinits. A single 
block may contain many thousand acres. 

(2) Compartment — An organisation unit or small artificial subdivision for 
purposes of location, administration, and silvicultural operation. (G., Abteil- 
ung, Jagen (Prussia). F. Parcelle.) 

(3) Lot — A small silvicultural subdivision of a compartment, differing in 
composition, age, or character, requiring different treatment from the main body 
of the compartment; temporary if due to accidental, pcr)nancnt if due to site 
conditions. (Synonyms: subcompartment. G., Unterabteilung, Abteilung 
(Prussia).) 



* Wolff, M. H. (Journal of Forestry, 1920, pp. 486-497). 



Management and Administratiz'e Subdivisions 25 

31. Discussion of Block, Compartment and Lot.* In figure 2 (P. W. C.) 
would probably form one block including the entire watershed but excluding 
the townsite (T). Area (P) would be divided into compartments a, b, c, d, 
and e, as indicated by dotted lines. The lots would probably not be necessary 
in a protection forest. 

(i) The boundaries of the block will ordinarily be topographic features 
such as watersheds, where the block would correspond to the logging unit 
rather than artificial subdivisions such as townships. The block should assist 
in the general location and classification of estimates and forest descriptions, 
but for larger areas than for compartments. Whether the topographic 
boundary will be a stream or ridge will depend on the local method of logging. 
If the block is based on natural logging units, the estimates will be convenient 
for small timber sales. If larger sales, comprising many thousands of acres, 
must be made because of market conditions, the estimates of a number of 
blocks can be conveniently grouped where each block corresponds to a 
logging unit. 

Care should be taken to clearly distinguish block and working group since 
the two may frequently coincide. The working circle may even be identical 
with the working group and block if the area under a sustained yield in a 
working plan happens to have the same boundaries as the group or block. 

(2) The compartment for some time to come will be the smallest perma- 
nent subdivision in the West with boundaries clearly marked. These bound- 
aries may be artificial survey lines (corresponding to the western section 
lines), rods, or preferably topographic features, such as ridge crests or streams. 
In our western mountains compartments are really small secondary logging 
units. The formation of compartment lines, especially in highly intensive man- 
agement should, if possible, conform to type, broad lines of quality and age 
classes. Where compartments can be made to include uniform quality, type 
or age, it is obviously an advantage to do so, but age, type or uniformity of 
stand cannot be the governing factor. In the United States, compartments 
in surveyed fairly level country will ordinarily be six hundred and forty 
acres, and in unsurveyed country considerably larger depending on the topog- 
raphy. The size must depend finally on the intensiveness of management. In 
New England the compartment may be less than one hundred acres. 

(3) The lot (often termed sub-compartment) is always a subdivision of 
a compartment, coinciding with distinct stands or descriptive unit. Since 
compartments cannot recognize differences in age or quality, the lot may be 
mapped and described separately if intensiveness of management justifies. 
Its boundaries are usually not permanently marked in the field but even under 
the extensive conditions existing in the Western United States, the lot may 
be justified in level country (except in mere protection working groups) 
because of the ease of recording intensive estimates by 40-acre subdivisions. 
So far as practicable the compartment and not the lot should be the unit 

* The term lot, adopted by the S. A. F. Terminology Committee in preference to 
the English term sub-compartment, should not be confused with the local use of "lot" 
in New England and in government survej^s in the West. 



26 American Forest Regulation 

of description in extensive timber surveys. The separation into lots may 
be dictated by a change in quality and type, provided this w^ill not necessitate 
dividing the forest into such small units as to be impracticable of description; 
or age classes, if distinct enough to map. The lot as a silvicultural subdivi- 
sion without demarcated boundaries will always be of value as an intensive 
unit for timber surveys. In New England the lot may be separated in the 
forest. 

32. Definition of Administrative Subdivisions. Administrative subdivi- 
sions are district, forest, ranger district or range, patrol district or beat. 
These are defined as follows: 

District — Generically, any administrative unit; specifically, an aggregate of 
administrative units or forests for control and inspection purposes. 

Forest — An administrative unit, as national forest, state forest, or municipal 
forest. 

Ranger District or Range — Part of a forest, an executive unit under care of a 
ranger. 

Patrol District or Beat — An executive unit for protective purposes, under a 
guard or patrol. 

Administrative subdivisions thus comprise the entire system of tiational forests, 
districts of forests, one forest, a ranger district within the forest or tlie heat for 
the guard within a ranger district. 

33. Discussion of Administrative Subdivisions. Administrative subdivi- 
sions are made to facilitate administration rather than the regulation of yield 
and forest management. The entire system of national forests may be dis- 
tinguished from other public lands, or from forests managed under a separate 
bureau or department. For example, Indian forests, which are managed for 
the benefit of the Indians, may be segregated from national forests, or state 
forests. For convenience of administration these national forests have been 
divided into administrative districts* in order to facilitate the administrative 
control of the individual forests under supervisors. Each district is under the 
direction of a district forester assisted by a staff organization, divided in 
the United States according to lines of work, such as silviculture, operation, 
lands, and grazing. The forest is a distinct or connected unit or aggregation 
of units under a forest supervisor, who has immediate direction of the admin- 
istration** under the direction of the district office. The forest is divided into 
ranger districts, which are in charge of a district ranger. Where necessary 
to facilitate administration or protection, the ranger district may be divided 
into "beats, each in charge of a guard. 

34. Quiz. Define subdivision. 

What does the size of subdivisions depend upon? 
What kinds of subdivision are there? 



* For a discussion of administrative organization problems the student is referred to 
Forestry Quarterly, Vol. XIV, pp. 188-236, Forest Service Revenue and Organization, 
by T. S. Woolsey, Jr. 

** It will be useful to give the student definite acreage figures on administrative sub- 
divisions for Western and Eastern conditions. 



Management and Administrative Subdivisions 27 

What are management subdivisions? 

Define working group, and working circle. 

What is the distinction? 

When do working group and working circle coincide? 

What determines working groups? 

Discuss how working groups are affected by type, silvicultural system, rotation, size, 
market. 

What determines working circle? 

Define lot, compartment, and block. Discuss boundaries, size, value, and distinctions 
of each of these three units. 

How does block differ from working group? from working circle? 

When would they coincide? 

What effect will topography have on compartments and working circles in the West? 

What are administrative subdivisions? 

When would a guard's beat correspond to a block and to a working group? 



CHAPTER IV 
ROTATIONS— TECHNICAL, SILVICULTURAL, AND ECONOMIC 

35. Definitions of Rotation (and Felling Age). By rotation is meant the 
predetermined time or period during which it is intended to cut over a working 
group; the predetcrmi)icd approximate felling age of the stands. Rotation refers 
to the forest as a zvholc a}vd is usually expressed not by a definite year, but to the 
nearest decade. Felling age refers to the actual age of the stand when cut. 

The length of rotations depend partly on the object of the owner and are 
also determined by technical, silvicultural, economic, or financial considera- 
tions as limited by silvicultural possibilities. According to Fernow a rotation 
is "the time through which the crop is allowed to grow normally until cut 
and reproduced." 

The view-point in India, as expressed by D'Arcy,* is contrary to the 
European conception of rotation (except in selection forests in France), 

namely, " the exploitable age of a forest crop is the age at which the 

individual trees furnish the kind of produce most wanted." 

According to Endres,** 

"By rotation period or rotation is meant that time which elapses, under normal con- 
ditions, between the planting and the utilization of a stand. In the case of the working 
group the rotation is the average time of growing merchantable material which is the 
fundamental consideration in working plan calculations." 

Variations from the normal may be due to unusual silvicultural, financial 
or economic conditions. 

36. Not to be Confused with Cutting Cycle. Rotation is not to be con- 
fused with cutting-cycle in selection forests, which is the period elapsing 
between cuts on the same area. Obviously in selection forests the length 
of the cutting cycle has an important bearing on the amount removed, and 
the frequency of cut also has a direct bearing on the amount that is lost 
through decay; consequently, there is a tendency with intensive management 
to short cutting cycles of from five to eighteen years. With extensive man- 
agement longer cutting cycles are at present unavoidable. In Oregon western 
yellow pine a cutting cycle of 50 to 60 years has been tentatively adopted ; 
this will be decreased when the market and permanent transportation is 
established. A cutting cycle of 100 years for western yellow pine in Arizona 
certainly must be reduced as soon as possilsle. In France*** under most 
intensive conditions the cutting cycle is five to eight years ; under less 
intensive conditions, nine to eighteen years, and rarely more than this. The 



* D'Arcy, W. E., Preparation of Forest Working Plans in India, Calcutta, 1898, 3d 
Edition. 

** Endres, pp. 220-221. 

*** Woolsey, T. S., Jr., Studies in French Forestry, Chapter IX, John Wiley and Sons, 
1920. 



Rotations — Technical, Silvicnltural, and Economic 29 

cutting cycle* is usually a sub-multiple of the rotation; obviously the longer 
the cutting cycle, the greater the cut. 

37. Conception of Length of Rotation. The tendency is to have too 
narrow an idea of what length of rotation means : for example, if five-year-old 
transplants are used for a plantation (after clear cutting) which is allowed 
to grow one hundred years, the rotation in this case would.be one hundred 
years (the length of time the forest soil is used) and not one hundred and five, 
the felling age, that is the age of the trees, since the time the transplants 
were in the nursery would be omitted in the calculation of the rotation. Yet 
it is of course recognized that the length of the rotation is shortened by the 
use of well formed transplants simply because the stand matures sooner. 
Similarly frequent and early thinnings are of the utmost importance in 
reducing the necessary rotation because with thinnings the stand will mature 
earlier than if left unthinned. Efficient thinnings not only enable the forester 
to grow timber of a specified size in fewer years, but they increase seed 
production and promote earlier seed crops ; they decrease the date of the 
culmination of mean annual growth, and, as Endres puts it, 

"The greatest benefit is felt where the highest soil rent is maintained .... It is 
recalled that large, early yields produce large soil rent and vice versa .... A stand 
that has been thinned up to the "n" year will have higher value than one that has not 
been thinned." 

It must be born in mind that while the forest as a whole may be managed 
according to specified rotations yet individual stands may be cut before or 
after the rotation age because of accidents, market conditions, etc. Still 
another point, worthy of emphasis, is that it is usually sufficient if the rotation 
can be established to the nearest decade ; it is splitting hairs to figure to 
the exact year when computing the rotation. 

Biolley in a recent treatise cautions against placing too much stress on 
age in considering rotations. 

". . . . they persist in confusing the age and the size of trees .... The age or 
time is only one of the factors of the result sought for (and not the principal one) 
. . . . The other factors are: the suitable role for each tree .... and especially 
the "savoir-faire" of the silviculturalist, the quality of treatment by means of which he 
utilizes and improves these factors .... The result sought for can only be 
production. The age is only an accessory." 

What Biolley** wants is really a flexible rotation to be modified by the silvi- 
culturalist so as to give the best possible production according to the demands 
of each group of trees, site, or local conditions of stand. "The Gurnaud 

idea consists above all in experimenting with the treatment " 

Such ideas are based on too intensive a treatment to be applicable for the 
United States, and it may often be unwise to give the officer in charge of a 
forest too much leeway. Regulation implies systematized control. 



* Refer to the discussion of cutting cycles in "Studies in French Forestry," already 
cited, pp. 226-228; also see chapter X, Part II of this volume for a more detailed dis- 
cussion of cutting cycles. 

** L'Amenagement des Forets par la Methode Experimentale at Specealement La 
Methode du Controle. Attinger Freres, Paris, par H. E. Biolley, 1920, p. 15. 



3© AjHcrican Forest Regulation 

According to Blascheck,* in India economic conditions necessitate an 
annual felling area; an average tree best suited to the objects of the manage- 
ment; sufficiently heavy fellings to insure regeneration; and, of less impor- 
tance, a felling cycle which shall be a sub-multiple of the rotation. 

38. Basic Policy for Rotations. One of the chief difficulties in computing 
rotations (and especially financial rotations) is that the forester must use 
present statistics or the trend of present statistics for calculations which 
pretend to answer management problems on the basis of unknown or roughly 
approximated conditions a half century or a century hence — obviously impos- 
sible to fathom. But the proper regulation viewpoint is that the problem 
should be solved for the present on the basis of the best available present 
data with the assumption that when the working plan is systematically 
revised, these calculations will be recomputed and brought up to date. The 
fact that a revised and altered answer to the rotation problem will be certain 
is no reason for not doing our best with available statistics. As a matter 
of policy it is often safe to also estimate future conditions, based on the 
trend of economic conditions, rather than to follow blindly present stumpage 
prices, present cost values, present current interest rates and market require- 
ments for forest products. The best regulation implies some attempt at 
fathoming the future. We know from past history that forest conditions 
will change ; therefore to follow blindly present conditions, we will arrive at 
the least accurate predictions. There is a via media between following 
today's data on the one hand and on the other of making unwarranted guesses 
at the future. Moreover we must realize that our calculations are at best 
approximations and therefore the minutiae may often be omitted with profit 
and propriety. American foresters, in striving for details, are apt to lose 
sight of the goal. 

39. Mean Rotations for an Entire Stand. The forester must (in theory) 
distinguish in intensive regulation (as for example in parts of New England) 
between the rotation for a particular stand and the rotation for a working 
group which is composed of a number of stands of varying quality, but in 
the West (in Northern Arizona for example) a rough general average rota- 
tion for portions of an entire region, will usually be a sufficiently close approx- 
imation for conditions prevalent while National Forests are being organized. 
Even in a selection forest such as Chamonix the French prescribe one tech- 
nical rotation for Norway spruce and larch based on a rough proportion of 
the length of time it takes to grow the two species, and weighted according 
to the aggregate volume present. This rightly emphasized the futility of 
minute mathematical calculations for the solution of a problem which only 
demands an approximate answer. 

40. Kinds of Rotations. The following kinds of rotations are of value in 
the United States and are listed in the order of extensiveness: 

(i) Technical, maximum of material for a certain purpose and size. 
(2) Silvicultural, based on limitations of species to reproduce or to resist 
decay. 



* Blascheck, A. D., "The True Selection System" (Indian Forester, 1913. Pp. 427-430). 



Rotations — TecJinical, Silvicidtural, and Economic 31 

(3) Economic, maximum average volume production gauged by culmina- 
tion of mean annual growth of stands. 

(4) Financial, divided into : 

a. Maximum forest rent or highest mean annual net money income 
(disregarding interest). 

b. Maximum soil rent or highest returns per dollar invested (with 
compound interest). 

41. Definition and Discussion of Technical Rotations. Technical rotations 
attempt to produce the maximum of material suitable for a certain purpose and 
of a given size, such as railroad ties, mine-timbers, or sazv-logs. 

Technical rotations in the United States are of more than mere historical 
interest. A technical rotation, especially under conditions existing today in 
the West, might give the correct answer. Take the case of a watershed 
which is most suitable for producing railroad ties, because railroad ties alone 
could be floated down a drivable stream, the sole means of transport ; here 
a technical rotation based on the length of time it took to grow ties of given 
dimensions, is clearly indicated. The exact length, in this case, would depend 
on the most suitable period for growing the quality of tie which yielded the 
largest net return on the investment, not taking into consideration com- 
pound interest charges* unless the data for financial calculations were 
available. 

In French Government selection forests technical rotations are usually 
chosen so as to produce the kind of material most in demand by the public, 
and to support local industries vital to the economic life of the locality. This 
kind of rotation, under the conditions existing in the Vosges, Jura, or Alps, 
where large sized saw logs are required, has been severely criticised by 
certain German foresters because of the financial losses usually involved; 
but with public forests it is usually better policy to put national needs above 
narrow conceptions of financial gain; so it is held that for National Forests 
the French policy is fully justified. A somewhat broader German viewpoint, 
as expressed by Endres,* is as follows : 

"Were we to apply the technical rotations to even-aged high forests, producing mainly- 
large timber, great financial losses would take place. However the policy of bringing 
about a mixture of species in order to meet market requirements or demands is 
apparently correct .... It is in keeping with sound forestry because it also main- 
tains soil fertility .... The technical rotation may also be used by the state for 
social and political reasons .... but the technical rotation can only be recognized 
when production costs .... are of no consequence to the owner." 

42. Illustrations of Technical Rotations. One of the earliest examples of technical 
rotations, for use on national forests, is that for western yellow pine, established in 
1909. According to Woolsey,** 

"If only timber of the lower grades is produced, export shipments will sufifer. It is 
therefore particularly essential, on account of the long hauls and consequent heavy 
freight rates, that a fair proportion of higher grades be supplied .... The best 
rotation cannot be predicted until after regulated cutting .... Tentatively, a 
rotation of 200 years is recommended." 



* Korstian, C. F., Manuscript Report, files of Forest Service, District III. 
** Woolsey, T. S., Jr., Western Yellow Pine in Arizona and New Mexico (Forest 
Service Bulletin loi, 1910, pp. 48-51-52). 



32 A)ncrican Forest Regulation 

Overmature stands of this species are from 250 to 400 years in age. At 200 years the 
average tree is about 21 inches in diameter and it is argued: 

"All available figures indicate that it will take 200 years to grow saw timber. It will 
be seen .... that diameter growth begins to fall off at from 100 to 160 years, and 
that hei.qht growth declines from the mean annual from 170 years this is cer- 
tainly the minimum size (21 inches) that can be estimated to j'ield timber of fair quality 
that will justify shipment. With thrifty, well thinned stands, however, it is hoped the 
growth will be greater." 

Obviously such a long rotation will be reduced with more intensive conditions, but 
even an author, such as Schlich, agrees that with extensive conditions and slow growth 
maximum rotations prevail. The rotation in question was preliminary in character, and 
merely facilitated the use of rough formulae methods of regulating the annual cut, 
advisable at that time, crude though they may have been. Judging from Table 19 of 
the Bulletin,* on the basis of maximum mean annual growth a rotation of but 70 years 
might have been indicated, obviously impracticable, under the conditions enumerated. 

As a contrast to the preliminary technical rotation of 200 years for the production of 
western yellow pine saw logs, the following specific rotation problem arose on the 
Pecos National Poorest in Northern New Mexico and is instructive: 

The** rotation and cutting cycle will be adopted which will yield the product having 
the highest monetary stumpage value, involving a combined technical and financial 
rotation." 

It was found that the greater the per cent of hewn ties in the final cut, the greater 
the stumpage value. Consequently, a rotation to produce this result was recommended 
and the problem was to find out from growth studies the size when western yellow 
pine (and other local species) produced the largest number of the most profitable sized 
ties. It was found that 14 and 15 inch trees were the optimum tie trees, because "trees 
less than 14 inches yield no square ties and no firsts." There was a wider margin of 
profit on the firsts than on the seconds. With this data as a basis the rotation estab- 
lished was the approximate number of years it takes to grow a western yellow pine 
tree 14 inches in diameter breast high — in this case 120 years. An average rotation 
was established on the basis of the dominant species, since it was considered impracti- 
cable to have separate rotation for different trees. The conclusion was also reached 
(as was to be expected) that "the shorter the rotation, the freer will be the forest 
from disease." (See also Silvicultural Rotations.) 

The factor of the size and quality of boards in the determination of rotation must be 
considered. For example, in the case of loblolly pine, 20 to 30 years would be a suffi- 
cient rotation, if round-edged box boards are desired; 35 to 40 years if part of the 
product must be a fair grade lumber; and 50 to 100 years if a considerable per cent of 
lumber of the best grade is to be produced.*** 

Short teclmical rotations may be chosen for the production of cordwood, mine props, 
pulpwood, fence posts, telephone poles, box boards, and such classes of product which 
can be grown in less time than can large sawtimber. 

43. Definition and Discussion of Silvicultural Rotations. Sihu'iilfiiral* 
rotations are based on the limitations of the species to reproduce or to resist decay. 
If a species produces seed prolifically between seventy and one hundred 
years of age, and regeneration must be by natural means, it would be logical 



* Woolsey, T. S., Jr., Western Yellow Pine in Arizona and New Mexico (Forest 
Service Bulletin loi, 1910, pp. 48-51-52). This rotation of 200 years has been confirmed 
by recent investigations. 

**Korstian, C. F., Hewn Tie Versus Saw Timber Rotations ((P. S. A. F. Vol. XI, 
1916, p. 315). 

***Ashe, W. W., Forest Management of Lol)lolly Pine. 1914. 

* Termed physical rotations by William Schlich in his Manual of Forestry, Vol. Ill, 
191 1, pp. 200-201. 



Rotations — Technical, Silvicultiiral, and Economic 33 

to limit the rotation to within those periods. In sprout forests a silvicultural 
limitation to the rotation chosen would be imposed by the limit of power to 
sprout. In case the coppice failed to sprout after it reached an age of seventy 
years and the treatment had to be simple coppice, naturally the forest would 
suffer, if a rotation of over seventy years were chosen. In this case silvicul- 
tural factors would be an absolute bar to a longer rotation. 
According to Endres* 

"Some believe it to mean the rotation which would leave the stand with complete 
reproduction.** With high forest (that time) was when the seed production was 
largest and when the soil was most receptive. With coppice it was within the sprouting 
limits of the stumps .... Others believed the rotation to mean the time when the 
stand is silviculturally mature or when the growth stopped." 

As a matter of fact if the rotation is an economic or financial one this 
factor of loss from rot will usually be eliminated because any intensive rota- 
tion (economic or financial) will fall before rot is a menace. The danger 
from rot, however, must be carefully considered when high quality saw 
timber is grown under a technical rotation or where the rotation is lengthened 
in protection forests. 

There is also the limit placed by decay, but strictly silvicultural rotations 
are of little real*** importance unless considered in connection with other 
kinds of rotations. Silvical requirements for reproduction or to avoid decay 
or other losses must perforce limit all rotations but rarely are the sole deter- 
mining factor. 

44. Illustrations of Silvicultural Rotation Limits. As Meineike* points out: 

"If a species such as white fir shows an increasing amount of defect after eighty years, 
a rotation should certainly not be chosen that would neceiisitate holding stands beyond 
this period; to do so would court unnecessary loss through decay." 

This factor of rot will be found to set a limit to the feasible rotation for other species. 
With western yellow pine Long** found, 

"that during the blackjack period (up to 180 years) the trees are practically free from 
this rot" (western red-rot) .... "while trees over 200 years old show a much higher 
percentage of rot than the younger trees (blackjack) .... It is a fundamental fact 
that the older a tree is, the more liable it is to be attacked by heart-rotting fungi." 

The following table by Zon*** furnishes another excellent illustration of a combined 
technical and silvicultural rotation: 



* Endres, p. 244. 

** Roth, Filibert, in his Foiest Regulation terms this a physical rotation. He also 
mentions a natural rotation which "is the natural life of the species, which hardly 
deserves separate nomenclature or description." 

*** Recknagel, A. B., in The Theory and Practice of Working Plans, 1913. New York, 
PP- 39-40, mentions also a latent rotation which hardly deserves the term rotation; he 
defines it as "just double the average age of the working figure" (working group). 

* Meineike, E. P., "Forest Pathology and Forest Regulation" (Forest Service 
Bulletin 275, 1916). 

** Long, W. H., A Preliminary Report on the Occurrence of Western Red-Rot in 
Pines Ponderosa (Plant Industry Bulletin 490, 1917. pp. 7-8). The term pathological 
rotation seems superfluous. 

*** Zon, R., "Chestnut in Southern Maryland" (Forest Service Bulletin No. 53, 1904. 
P- 31). 



34 American Forest Regulation 







T 


rees from 


see 


:d 


Coppice 


Kind of pro 


duct 




(age years) 




(age years) 


Post 






27 






14 


Tie 






41 






29 


Pole 






49 






38 


Rail 






54 






43 


According to Zon, 















"Chestnut (sprout) is not suited to the production of large timber on account of its 
unsoundness and short clear length when it has reached the desired size. Therefore 
even if large timber is desirable, chestnut should not stand longer than seventy to 
eighty years, and coppice will then fill requirements better. Only in exceptional cases, 
.... should chestnut be left standing ninety years or more." 

According to the above table, if the main product is chestnut ties, the rotation, for 
trees grown from seed, must be at least forty years; but if coppice, only thirty years. 

With sprout reproduction, as has been explained, the forester cannot delay cutting 
until the sprouts are no longer vigorous. Therefore, mean maximum ages can be 
established, bej'ond which it w-ould be dangerous to hold sprout stands. For chestnut 
(prior to the chestnut blight) this maximum age was approximately 75 years; for 
chestnut oak, 45; for other oaks, 25 to 35 years. As to choice of material, whether 
cord wood, lumber, ties or poles, it is simply a local problem which must be worked 
out according to the conditions of haul and stumpage prices. According to the growth 
studies made by Frothingham,* the average annual growth culminated for chestnut on 
sites I and 2 at 35 years; on site 3, at 40 years; for chestnut oak on sites 3, at 40 years. 
The general conclusion was reached that for ordinary hard wood sprouts in Connecticut 
a rotation from 30 to 40 years was advisable, but that (prior to the chestnut blight) 
chestnut sprouts may be held up to 75 years if lumber is to be produced. This shows 
the correct application of this technical phase (in connection with other factors) before 
the decision is reached as to the rotation period. 

45. Definition and Discussion of Economic or Quantitative Rotations. 

Economic (or quantitative) a'otations attempt to secure the maximum average 
volume production per acre and are based on the culmination of the mean annual 
growth read from yield tables, and not on the maximum growth of individual 
trees. 

The point in the yield table, where the mean annual growth** culminates, 
indicates the economic rotation. This point is readily determined after it 
has once been established what part of the tree is to be included as volume. 
Expressed as a simple formula it is as follows: Final yield -\- intermediate 
yield -^ number of years. In the United States when the board foot unit is 
used this culmination of mean annual growth will vary, (i) according to 
the log rule used, (2) depending on the utilization standards, especially as 
regards top cutting limits, and (3) according to the class of material which 
is included in the computations of volume. Because of these complications 
it is desirable when practicable to use other units, such as the cubic foot. 

(i) Effect of Log Ride. With a log rule which gives large volumes for 
small sized trees, the tendency would be to shorten the rotation because with 
such a rule the mean annual growth would culminate earlier. With a rule 



* Frothingham, E. H., Second Growth Hard Woods in Connecticut (Forest Service 
Bulletin, 1912, p. 45). 

** See Forest Mensuration, H. H. Chapman, for the curves of current annual and 
mean annual growth. 



Rotations — Technical, SilvicnUural, and Economic 35 

tliat put proportionately small values on small logs and too generous volumes 
on large logs, the culmination (other factors being equal) of mean annual 
growth would be retarded and consequently the rotation would be lengthened. 

(2) Utilisation Standards. The smaller the top cutting limit, the shorter 
would be the indicated economic rotation because with a larger top cutting 
limit a longer time must elapse before an appreciable proportion of the tree 
is merchantable. 

(3) Class of Product. If small sized ties are the most desired product, it 
clearly follows from (2) that the economic rotation will always be shorter 
than if a larger class of product must be marketed. The culmination of the 
mean annual growth of small ties (even if expressed in the common factor 
of board feet) will be earlier than if the culmination in hoard feet is computed 
on the basis of saw logs. This is a phase which is also present in technical 
rotations. 

According to Munger,* 

"It is the policy of the Federal Government to administer the public forest lands in 
such a way as to perpetuate as forest all the land which is better suited to the produc- 
tion of timber than anything else, and to make it yield for all time the greatest quantity 
and the best quality of timber." 

46. Choice of Economic Rotation with Illustrations. The most satisfac- 
tory basis for a choice of economic rotation is the total production of material 
according to a specified unit of product, such as board feet, for a specified 
size of sawtimber, cubic feet (or cords) for pulp wood, linear feet of converter 
poles with a top limit specified, or cords of fuel. Where, as usually happens, 
the product from the ripe tree must be in three classes, such as board feet, 
ties and cordwood, the gauge of quantity must be expressed in a common 
unit which can serve as a basis for the comparison of the standard volume 
at different ages; otherwise three different quantitative rotations might be 
indicated, which is impracticable because three classes of product are derived 
from one and the same tree. In such a case often the most logical procedure 
is simply to adopt a financial rotation (see Chapter V) since then the common 
unit of comparison will be the dollar. EndreS shows that the culmina- 
tion of the mean annual growth is earliest on the richest soils and it is well 
to bear in mind that, 

"The rotations on the better sites are often shorter than financial rotations for 
unthinned high forests where the market conditions are bad." 

According to European yield tables** the economic rotations are approximately as 
follows: 

Soil quality Pine (Schwappach) Spruce (Baur) Fir (Schuberg) Beech (Schuberg) 
— Age in years when mean annual growtli culminates — 
I 35 50 55 70-75 

II 40-45 60-70 60-65* 80-S5 

in 50-60 70-80 70-75 85-95 

IV 75-80 60-80 85-90 95-100 

^' 95-105 loo-iio 



* Munger, Thornton T., Western Yellow Pine in Oregon (Forest Service Bulletin, 
418. 1917, p. 36). 

'^* Endres, p. 245. 



36 American Forest Regulation 

The above figures, however, only serve to illustrate that the rotation which produces 
the largest amount of wood is not necessarily the best, except perhaps in localities in 
which coal is scarce and transportation very poor. As Endres puts it, 

"In the present age of commercialism, it is no longer a case of the greatest volume 
but of the highest money return for the best product that is the controlling factor in 
fixing the rotation." 

Whether this will apply to American conditions is a question. If there is a national 
timber shortage, it would be easy to justify rotations that would produce the greatest 
quantity of product required by the nation. 
Illtistratiflus of cco)iomic rotations. The Forest Service (District 1) determined that 

"The maximum yield for (western) white pine under average conditions occurs at 
120 years and the rotation has been fixed accordingly. In the case of lodgepole pine, 
however, another consideration enters into the problem. It has been determined that 
at the age of growth culmination the trees are too small to supply the local demand. 
Hence, a longer rotation than indicated upon a straight yield basis has been established." 

This determination of the rotation of lodgepole pine is of interest because the rota- 
tion could not be established solely on the basis of maximum mean annual growth, 
since at that time sufificient merchantable material would not be produced. The objects 
of management in this case were not only watershed protection but also a maximum 
sustained yield for merchantable timber of the most desirable sizes. According to Mason* 

"The length of the rotation .... is determined by the rate of growth .... and 
the purpose for which the wood is to be used. Because of the slow growth of lodge- 
pole pine and the necessity of raising large sized ties, a longer rotation must be chosen 
than would be indicated by the culmination of mean annual growth at 70 to 90 years 
on different soil qualities. A rotation of this length, however, gives few trees 9 inches 
or more in diameter and is, therefore, too short." 

If the material was cut to 6 inches in the top, the board foot mean annual growth 
culminated at 130 years, while if cut to 8 inches in the top, the culmination is delayed 
to from 200 to 210 years. At 130 years only 75 of the material produced is 8 inches or 
more in diameter at the top end, while at 200 years nearly 9/10 of the material produced 
is merchantable. The author therefore concludes that, 

"The mean annual growth in board feet to a 6 inch top is nearly at its maximum at 
140 years, when 53 per cent of the scale material is 8 inches or more in top diameter 
.... Such a rotation is the best for normally stocked lodgepole stands on average 
sites in Montana." 

This is a sound method of analysis, but with thinnings the limitation as to size would 
probably be largely done away with because there would be fewer trees but with a 
larger size in the top. There is no objection to basing the economic rotation on the 
culmination of mean annual growth taking into account only trees of the most desirable 
size. 

In a quality I second growth white pine** stand, at 55 years of age the mean annual 
growth is 1000 board feet; at 60 years it has risen to 1003 board feet and at 65 it is 
1002. In this case the quantitative rotation for first quality soil would be sixty years 
if based on the board foot yield. For the same quality of soil in this table, but for 
cubic feet, it will be noted that the culmination is at fifty-five years. A still different 
culmination of mean annual growth would have occurred if the board feet had been 
computed by a different log rule or with different cutting limits in the type or different 
standards of utilization. It is therefore evident that in determining a quantitative rota- 



* Mason, D. T., Utilization and Management of Lodgepole Pine in the Rock Moun- 
tains (Forest Service Bulletin 234, 1915, 22-3. Special reference is made to table 12, 
p. 22). 

** Reference is made to table 7, page 24. in White Pine Under Forest Management, 
by E. H. Frothingham (Forest Service Bulletin 13, 1014)- 



Rotations — Technical, Sih'icultural, and Economic 37 

tion it is necessary to give the exact data upon which it is based. Quantitative rotations 
are never based upon current growth. 

According to the Forest Service (District 6), 

"In the Douglas fir region we are now operating on a tentative rotation of 100 years. 
Our overstock, however, is so large that we are not very vitally concerned at present 
with the length of rotation .... In the yellow pine region we have assumed a 
rotation of 180 years with a cutting cycle of 60 . . . . Until we have more specific 
data as to the rate of growth after cuttings (making allowance for increased growth, 
normal loss, etc.) and know more about the silviculturally most desirable method of 
cutting, I don't see how we can arrive at the ideal rotation and cutting cycle." 

Hawley's* conclusions (basis not given but probably economic) as to the proper 
rotations for intensive forestry around New Haven were as follows: 

Hardwood type 60-80 j'ears 

Hemlock type 80-100 years 

Pine type 50 years 
These conclusions are obviously tentative. 

According to Chapman's investigations** Ashley County, Arkansas, the shortleaf pine 
cut on an economic rotation should be grown in 100 to no years; probably in the 
majority of cases the rotation indicated by this local study will be less rather than more. 

No mention was made by*** Graves of rotation, but after showing that trees were 
merchantable for pulp down to five or six inches inside bark on the stump, he analysed 
the diameter limit of cutting. He showed that if spruce trees were cut to six inches 
there would be 75 years betvveen cuts of equal size; if to 8 inches, 50 years; while if 
cut to 10, 12 or a 14 inch limit, there would be a correspondingly shorter interval 
between equal cuts. He selected 10 inches in this case as the diameter limit because 

"The owners wished to obtain the greatest possible immediate return without seri- 
ously impairing the productive capacity of the forest and are willing to wait for a longer 
period for a second cut." 

Such a diameter limit corresponds roughly to a rotation of 165 years. This has the 
character of an economic rotation, but the fallacy and danger of using any diameter 
limit in irregular stands must be recognized. 

The Norway pine mean annual growth culminated at 130 years, curiously enough on 
all sites. This is probably due to errors in growth data since ordinarily the poorer the 
soil the later the* culmination of mean annual growth and hence the longer the 
economic rotation. 

According to Mattoon,** rotations depend largely on (i) The age when the mean 
annual growth is greatest, (2) The kind of material desired, and (3) The total cost of 
producing the material. 

Such a conception involves an economic rotation, a technical rotation and a financial 
rotation, but this same writer concluded that the most reliable basis is the time when 
the mean annual production is greatest (i.e., economic rotation). For short leaf pine 
Mattoon concluded that the economic rotation for site II stands in North Carolina 



* Hawley, Ralph C, A Working Plan for the Woodlands of the New Haven Water 
Company (Yale Forest School Bulletin 3, 1913, p. 25). 

** Chapman, H. H., Prolonging the Cut of Southern Pine (Yale School of Forestry, 
Bulletin 2, 1913. p. 8). 

*** Graves, H. S., Practical Forestry in the Adirondacks (Bureau of Forestry, 
Bulletin 189Q, p. 64). 

* Woolsey, T. S, Jr., and Chapman, H. H., Norway Pine in the Lake States (Forest 
Service Bulletin 139, 1914, p. 26). 

** Mattoon, W. R., Short Leaf Pine, Its Economical Importance, and Forest Manage- 
ment (Forest Service Bulletin 308, 191S, p. 32). 



38 American Forest Regulation 

was 90 years; for sites in Arkansas, 100 years, but for New Jersey, 45 to 50 years. 
This is for sawtimber. If the mean annual growth culmination is based on total volume, 
without consideration of size, then the culmination comes 20 to 30 years earlier than 
when sawtimber must be produced; on site I, at 50 to 60 years, on site II, at 60 to 75 
years, on site III, at 85 years. These rotations would be decreased by 15 to 30 years, 
with early and frequent thinnings. The specific rotation recommended for conditions 
on the Arkansas National Forest, where the aim was "to produce the sort of material 
most needed by the people, which is mostly medium sized sawtimber," is 90 3'ears, 
which will produce an average tree of 15.9 diameter containing 240 board feet. 

47. Quiz. What is a rotation? 

Explain cutting cycle. 

What affects the length of rotation? 

Should the rotation be based on present statistics or on possible future changes? 

Discuss intensive and extensive rotations. 

Define technical, silvicultural, economic rotations. 

What kinds of financial rotations are there? (see chapter V). 

How do economic rotations differ from those based on the forest rent theory? 

Illustrate when technical rotations are advisable. 

Is this kind of rotation best suited to public or private management? 

Why do technical rotations sometimes entail financial losses? 

Is it safe to base the decision as to the length of rotation purely on technical grounds? 

Illustrate a silvicultural rotation? 

Is this a safe basis upon which to base a rotation? 

How are economic rotations established. 

How is it affected by log rule, utilization or class of material harvested? 

Would an economic rotation for pulpwood closely agree with the best financial rota- 
tion (forest rent)? financial rotation (soil rent)? (see chapter V). 

Discuss and comment upon the economic rotations for various species and show- how 
these will be modified in the future. 



CHAPTER V 
FINANCIAL ROTATIONS 

48. Definition of Financial Rotations and Related Subjects. Before defin- 
ing financial rotations let us repeat the definition for forest rent and soil 
rent. 

Forest rent is the net income from a forest organised for sustained yield with- 
out interest charges on the forest capital, — bookkeeper's- balance, — the forest, i.e., 
soil -with a stand or growing stock, being conceived as the forest capital, and the 
rent as the total interest earned thereon. (G., Waldrente.) 

Soil rent is. that part of the income (or balance) from a managed forest which 
remains as interest on the soil capital alone after all expenses with compound 
interest have been deducted, the soil alone being conceived as the capital. (G., 
Bodenrente.) 

Our definition then is : 

Financial rotations aim at securing the highest monetary return. This rotation 
will vary depending on whether the return is figured on the basis of forest rent 
or soil rent. 

Financial rotations introduce considerations of cost and attempt at securing 
either the maximum forest rent or maximum soil rent. The maximum forest rent 
rotation is that rvhich yields the highest net mean annual net money return without 
compound interest; the maximum soil rent rotation is that which yields the highest 
return (at compound interest) per dollar invested.^ 



* Before discussing financial rotations let us bear in mind the definitions for capital 
and value in their various phases (As explained in the preface, the terms and definitions 
follow the form adopted by the S. of A. F., see J. of F., Vol. XV, 1917, pp. 68-101): 

This factor of production in the forestry business is variously figured according to 
what parts of the investment are referred to and what basis of valuation is applied. 

Fixed capital refers to such kinds of capital as are not used up in production, like 
the soil. 

Working or operating capital refers to money capital needed to supply current 
expenses in operating a forest. 

Soil capital refers to the value of the soil figured in various ways. 

Stock capital refers to the value represented by the wood material of all stands com- 
prising a forest or working circle. 

Forest capital refers to soil capital and stock capital combined. 

Base capital may be used following the precedent of Pressler in his index per cent 
for the combined soil and working capital. 

The capitals may be based upon various kinds of values, and to secure a definite 
meaning, the term must be qualified by the method by which its value was determined. 

The following values may be differentiated: 

Investment value — the purchase price or the actual expenditures or investments that 
have been made in acquiring or creating the property with interest, less incomes actually 
derived from it, with interest. (G., kostenwert). 

Sale or exchange value — the market price based on statistics of actual sales: a special 
kind of sale value is the forced sale or wrecking value that can be obtained by exploita- 
tiorw of saleable parts (see stumpage value) (G., verkaufswert; F., valeur venale). 



4° 



American Forest Regulation 



49. (A) Rotations for Maximum Forest Rent or Highest Mean Annual 
Net Money Return. This form of rotation is exactly similar to the economic 
(or quantitative) rotation except that the yield unit is expressed in money 
with the costs of operation deducted — a common standard of comparison. 
The cost of establishing the stand is deducted so that the net mean annual 
per acre income can be figured for each decade. The decade with the largest 
mean annual return is the forest rent rotation indicated. This is a more 
intensive form of rotation than the economic (or quantitative) already 
described but less intensive than a financial rotation based on the soil rent 
theory described later, where the costs are figured at a definite rate of com- 
pound interest and all costs and returns discounted to a definite date so as 
to have a uniform basis for comparison. 

The forest rent formula is as follows: 

(Final and intermediate returns) — (expenditures), . , ' ,. , 

-^^ \ -r — or using the terms listed. 

number oi years 

(F$ + I$) — (C$ + Ai$). 

N 

50. Illustrations of Maximum Forest Rent. As yet there are few examples in Ameri- 
can forestry of rotations for the highest mean annual net money return. The 
following table is from Endres*: 

Table 2. Synopsis of gross returns, expenditures, and mean annual net returns in 
dollars per acre for a fully stocked quality III spruce stand. 



Rotation 
years 


Gross Returns 1 


Expenditures 1 


Net ^""^"/ 

Returns ^"""^^ 
returns 


Mean 


Final 


Inter- 
mediate 


Total I 


Planting 


Adminis- 
tration 


Total 


annual 
returns 


30 

40 

50 

60 

70 

80 

90 

100 

no 

120 


$ 48.30 
109.10 
188.00 
259.00 
345-30 
451 00 
554-20 
666.20 
759-40 
821,80 


$ -.- 
4.10 
12.40 
25.20 
38.00 
51.00 
64.60 
77-80 
88.80 
98.20 


$ 48.30 ' $8.00 
113.20 8.00 
203.40 8.00 

284.20 ; 8.00 
383.30 8.00 
502.00 8.00 
618.80 j 8.00 
744.00 8.00 
848.20 8.00 
920.00 8.00 


$18.00 
24.00 
30.00 
36.00 
42.00 
48.00 
54-00 
60.00 
66.00 
72.00 


$26.00 $ 22.30 $ 5-89 
32.00 ' 81.20 " 8.12 
38. 00 1 162.40 7-78 
44.00 1 240.20 9 31 
50.00 333-30 1 11.27 
56.00 446.00 11.08 
62.00 556.80 "92 
68.00 676.00 9-82 
74.00 774.20 6-58 
80.00 ll 840.00 


$0.74 
2.03 
3-25 
4.00 
4.76 
5.58 
6. xg 
6.76 
7.04 
7.00 



In the preceding table the maximum forest rent {mean annual) falls at no years when 
it amounts to $7.04 per acre per year. The maximum current income comes between 90 
and 100 vears. 



Stock or siumpagc value — based on sale value of material ready for immediate utili- 
zation (Synonym, utilization value) (G., nutzungswert). 

Expectancy value — the present worth of all estimated or expected future net earnings 
(discounted to the present); the capitalized net income value (G., erwartungswert; 
F., valeur d'attente). 

Rent or yield value — a value, determined by capitalizing, with a demanded rate of 
interest, the yearly or intermittent net return possible to be derived from a managed 
property. (See forest rent and soil rent) (G., bodenrentierungswert, waldrentierungs- 
wert). 

* This table was taken from Endres, Lehrbuch der Waldwertrechnung und Forst- 
stative, page 233. Marks per hectare were reduced to dollars per acre by dividing by 
10. The yield was calculated for spruce, quality 3. This table has been u'ed in slightly 
diflferent form by other American writers. 



Financial Rotations 



41 



Endres* gives another method of figuring what he terms "value increase per cent 
which is virtually growth per cent expressed in money with expenditures deducted. 
His calculations are as follows: 

Value per cent at no years .-=100 (i + $§Mo — $8^ ^ _ ^ ^^or^ 

no $75940 

Value per cent at 100 years =-^°° ( i + fe^o — $8_oo . ^ 1,105% 

100 $666.20 

"The stand is therefore not ready for cutting because 1.105 is greater than 1.006," as 
held by the above mentioned author. 

Value per cent at 120 years =: '^ (i + ^-fP-^=^^^) = .925%. Here, 

120 $821.80 

"The stand has passed the cutting period because .925 is less than 1.006." 
This formula may be expressed as follows: 

Value per cent = ^°^ / , Intermediate yields — planting costs \ 

rotation ^ final yield 

This is a formula of technical interest but its use would not be necessary because the 
rotation is more readily determined by a direct computation of the net mean annual 
returns for different rotations. Where true per cents are calculated, other factors must 
enter in. 

51. Distinction Between Forest Rent and Soil Rent with Illustrations. 

The distinction between forest rent and soil rent rests on the difference 
between income per acre without interest and income per dollar invested with 
compound interest. This difference is thus discussed by Endres: 

"The manner in which interest accumulates is shown in the following table, figured on 
a beech high forest (with interest at only 2%): 

Rotations 30 

Forest rent $0.74 

Soil rent $0.23 

Interest on capital .... $0.51 

"In a beech high forest the largest mean annual forest rent per acre gave a total of 
$7.04 at a rotation of no years. When 2% interest is used then the total of the soil 
rent (value) in the same year is $85.50, making the annual soil rent $85.50 X 0.02 ^$1.71. 
This equals, 

f soil rent $1-71 

/■ -V ■' interest on the accumulated wood capital 5.33 

I 

I Total $7.04 

The largest soil rent value is figured for a 80-year rotation with $98.80. The mean 
annual forest rent for the same rotation carries annually $5.58 per acre. This gives, 

r $98.80X0.02 $1.98 

C80 vear-") - '"Merest on the accumulated wood capital $3.60 

I Total $5.58 

"The true "rent" witicli is possible throii,g,h the managing, of the forest income, lies in soil 
rent, which is determined by adhering to the rotation of the highest forest rent. The difference 
between soil rent and forest rent, i. e. the interest on the accumulated zvood capital, is nothing, 
more than an expenditure zvhich is necessary to make in producing the soil rent. The forester 
has to subtract this from the forest earnings, or, commercially speaking, to equalize 
expenses incurred on accumulating debts. 

"In our example the forester has a yearl}^ income of $7.04 per acre by adhering to a 
no-year rotation. If he figures correctly, he will subtract $5.33 as costs of the enter- 
prise and he will actually net only $1.71 (soil rent). By adhering to the financial 
rotation he earns an average of $5.58 per acre. The expenses demand only $3.60; so 
he nets $1.98. 



40 


50 


60 


70 


80 


90 


100 


no 


120 years 


2.03 


325 


4.00 


4.76 


.S..S8 


6.19 


6.76 


7.04 


7.00 


1. 00 


1.56 


1-75 


1.89 


1.98 


1-95 


1.88 


1.71 


1.47 


1.03 


1.69 


2.25 


2.88 


3 -60 


4.24 


4.88 


5-33 


5-53 



* Endres, p. 234. Since no comprehensive original work has been done in the U. S. 
on soil rent calculations, it was thought best to give a translation of the best German 
treatise on the subject. 



42 American Forest Regulation 

"The greater profit which the uoyear rotation has over the 8o-year rotation is only 
an ostensible one. In reality the 8o-year rotation brings the forester a greater net profit 
($1.98 — $1.71 =$.27) per acre over the iio-year rotation. 

"Tlie yearly loss, which the forester suffers through the shorter rotation .... is 
equal to the gain between soil rent and forest rent. 

"In consequence of the previous facts, it is evident that the Iiighest income in connection 
with area is made in managing for forest rent. 

"This is true when we consider forest rent as a clear profit. In reality this is not the 
case. The greatest part of the forest rent is made up of interest on stored-up wood 
capital that becomes larger, the longer the timber remains in the woods, i.e., the longer 
the rotation. This interest, as mentioned before, is no gain to the forester but is 
enterprise expense or debt that has to be met out of the forest rent. 

"In 'Handbook of State Investigations,' III Vol., p. 602, the following explanation is 
given of managing for forest rent: 'The followers of this idea figure the forest as a 
box out of which we can take, periodically, a sum of money called rent. How much 
this will require for expenses causes no worry.' The remarks by Bose, Urich and Baur 
agfiinst this, given in 'Centralblatt,' 1893, are of scientific interest. 

"The forest rent thus comes at no and the highest soil rent at 80. 

"We can also say that by changing the rotations which brought the highest forest 
lent we change conditions (that existed since the primeval world) since the forest has 
always been handled under this rotation. The forest owner, whether private or state, 
will necessarily suffer a clear loss. This is also true in a spruce forest with a working 
group of no acres; using a no-year rotation will give a forest rent of $7,038 X no = 
$774.20; using a rotation of 80 years gives a yearly forest rent of $5-58 X no = $613.25. 
The net gain in yearly forest rent amounts to $774.20 — $613.25 = $160.95. This gain 
however (if we consider soil rent) will be more than used up by the interest earned 
on the stored capital, that had been liberated due to an earlier rotation. This carries 
$5-33 capital at interest per acre for the no-year rotation, as follows: 
^5-33 s^ 1 10 = $29,315; 
$0.02 
and for the 80-year rotation, 

|3^^ XI 10 = $19,794.50, 

$0.02 
the excess ($29,305 — $19,794.50) being $9,510.50. The owner has this $9,510.50 as specie 
(gold coin) drawn out of the forest and can put it in the bank at interest. Should he 
get only 2% interest, he earns a yearly rent of, 

$9,510.50 X 0.02 = $190.21, 
which amount easily makes up the forest rent gain. The actual yearl}' income gained 
through shortening the rotation is shown as follows: 

80-year rotation, $613.25 -f $190.21 = $803.46 
no-3-ear rotation, $774.46 



Clear gain from 80-year rotation $29.26 

Should the forester receive a 3% interest rate on the liberated capital (this rate being 
quite possible), it will give an interest gain of, 

$9,510.50 X 0.03 = $285.31 
and thus the clear yearly gain will be, 

_ ($613.25 + $285.31) — $774-20 = $124.36. 
Now from the practical side a rotation cannot be changed so quickly in spite of the 
pecuniary gain on the liberated capital. Besides overstocking the local market, wliich 
may be of some importance, we also upset the normal handling and normal conditions 
of the stand. It is necessary (for such an undertaking) to formulate a definite working 
basis and allow time for the complete use of the liberated stock (timber). A primary 
consideration is the proper investment of the drawn out capital. If there is danger 
of not properly disposing of the capital, then it had better remain in the forest in spite 
of the fact that it earns no interest .... 

The fundamental principles of the Forest Rent Management as compared to Soil 
Rent Management are: 

"(a) The forest rent theory is determined by the rotation as based on the area. 
The fundamental dift'erence between the methods of rotation lies in the fact that the 
soil rent management discounts the intermediate earnings and costs to a definite period 
with compound interest, while the forest rent management simply adds and subtracts 
without considering compound interest .... 

"(b) The forest rent management .... is built up on future earnings and costs. 
If we want to determine the time the forest rent culminates in a 30-year-old stand, we 
have to consider the earnings and the costs that are expected to take place at 80 to no 
years, therewith figuring the rotation of the greatest forest rent. 

"Therefore the belief that the forest rent theory fixes with more* certaintj^ the rota- 



* When the forest becomes a "going concern" the opponents of the soil rent theory 



Financial Rotations 43 

tion period than does the financial (soil rent) rotation is fallacious and the adherers to 
this belief are misled. 

"(c) The rise and fall in earnings and expenses due to price changes has a pro- 
nounced influence on the rotation period. 

"An increase in operating costs and rise in stumpage value lengthens the forest rent 
rotation and vice versa. An increase of thinnings shortens rotations, whereas a lessening 
of thinnings lengthens them. (Read, Loreh's, Handbuch der Forstwissenschft, II, 
p. 91.) 

"It is noticeable that a change in price level has more influence here than in the soil 
rent theory .... A very small price increase ($0.31) lengthened the rotation from 
no to 120 3-ears. 

"(d) The flexibility of the rotation period with change in price level carries with it 
the strict adherence to the principle that any excess or defective growth should be 
disposed of. 

"From this viewpoint the rotation of greatest forest rent has no advantage over the 
soil rent rotation. The advocates of the forest rent theory put it as a matter of fact 
that in the state forest operations the shortening of the rotations is done on the prin- 
ciple of highest forest rent. This assumption is ill founded. In actual practice the 
rotation of the highest forest rent is much higher than is usually accepted. 

"It is pointed out that Weber argues correctly when he shows that practical con- 
siderations must have weight in the choice of the rotation. Besides one must take into 
account, the growth of the final stands, the yield from periodic thinnings, average price 
per cubic meter, relative profit from different species, intermediate costs, cost of admin- 
istration and supervision, and state and municipal taxes." 

Kirkland* argues that if all age classes are present in a forest, it is not necessary to 
use compound interest in determining profit because, 

"Since we are determining the current annual results year by year, compound interest 
is not involved. In other words we are working on a forest rent basis; i.e., what will 
the forest earn each year on the investment? Particular emphasis should be laid on the 
fact that toda}^ we have large forests, and that any effective forestry work we do must 
be wy;h these forests. Therefore, we can best work on the forest rent basis. Any 
forestry we do on bare tracts will be insignificant." 

This viewpoint does not agree with the best European mathematical theory 
as has been seen by Endres's discussion of the relationship between forest 
rent and soil rent. With the present widespread forest destruction in the 
United States it would appear that we must deal with bare soil. For a more 
complete discussion of the subject see books on valuation. It should be 
emphasized however, that in the United States soil rent rotations will usually 
be rejected for silvicultural and policy reasons and not because soil rent is 
poor mathematics. 

The idea that financial rotations can be based on the grow^th per cent of 
single trees has not gained credence in America. Few would agree that 
yellow' poplar** "can be considered mature financially when their annual rate 
of increase in value becomes equal to the correct rate of interest on money." 
No definite number of years is mentioned as the rotation, but instead maximum 
diameters according to different costs of operation and different sites. 

52. (B) Rotations for Maximum Soil Rent or Highest Returns Per 
Dollar Invested. Here the criterion of profit is the maximum revenue with 
expenses deducted, but all statistics must be carried at compound interest 
at an estimated rate. The customary method of computation is to figure 
the expectation values for different ages ; the largest expectation value 



have more plausible arguments, but as a matter of fact if the forest devastation con- 
tinues in the United States there will be few forests that are "going concerns." 

* Kirkland, Burt P., Continuous Forest Production of Privately Owned Timberlands 
as a Solution of the Economic Difficulties of the Lumber Industry. (Journal of 
Forestry, Vol. XV, 1917, pp. 41-42.) 

** Ashe. W. \V., Yellow Poplar in Tennessee. 1913, p. 36. 



44 American forest Regulation 

denotes the most profitable rotation or the rotation of maximum soil rent. 
The following is a complete formula for expectancy or soil value: 

Expectancy or Soil Value (see table of symbols) = ^^~^^ _ (C$ + AE$) 

For further details see § ii6, page 92 of Forest Valuation by li. II. Chapman. 
According to Schlich,* 

"The expectancy value indicates the true economic value of the soil for 
forest culture because it is based upon the productive power of the land when 
used for the rearing of forest crops." 

For practical purposes, if only the rotation is to be determined (and not 
the actual soil value), the following formula is sufficiently accurate: 

„ , final yield + intermediate yields 

Jixpectancv value =^ -^ 

I . op" — I 

The reason why this formula is a judicious approximation is that annual 
expense has no real influence on expectancy value, the cost of formation and 
soil value almost none, and the yield from thinnings very little. There are 
two very important factors, namely, (a) rate of interest and (b) final yield. 

53. (a) What Rate of Interest Should Be Used? The rate of interest 
is the most important problem and has been made more confusing by the 
world inflation incident to the Great War. Low interest rates mean longer 
financial rotations than do high rates. Schlich** shows that (for a Scotch 
pine forest) if the interest rate was 2^/^% (the rate often chosen for catcula-- 
tions in England), there would be an indicated rotation of 80 years. Increase 
this rate to 3% and the rotation (based on the expectancy value) would be 
70, and if 4%, only 60 years. 

Most European authors agree in the theory that a forest which yields 
permanently the highest net annual income (with interest) is the greatest 
benefit to mankind, other things being equal. On the other hand, there is 
a tendency on the part of the individual (and still more so if the state is 
owner) to forget past interest expense, if by holding a stand to a longer 
rotation, the gross or apparent net yield per acre is increased. Only when 
past expenditures constitute an obligation which must be met, and hence 
earned, will the true financial relation between cost and income (with interest 
compounded) be the determining factor in the rotation. 

As a matter of fact no one would argue that the state should take financial 
profit as its sole object in forest management, but it is usually admitted that 
the public welfare may be best served by giving proper consideration to value 
production along with a regard for the obligation to raise the largest amount 
of product most keenly needed by the locality. The public forests belong to 
the whole nation and the object of a financial rotation should be the highest 
possible production of material both for present and future generations. One 
of the main drawbacks to a narrow conception of the necessity of following 
blindly a short soil rent rotation (untempered by sound silviculture) is that 
future production might be impaired. 



* Schlich, Vol. Til, pp. 127-129. 
** Vol. Ill, pp. 127-29. 



Financial Rotations 



45 



According to Roth,* 

(i) The "normal" forest of central Europe in ordinary rotations yields 
two to three per cent on the sale value of the forest. 

(2) This per cent is independent of site. 

(3) Beech and oak exceed pine and spruce (in rate of interest) on one 
hundred and twenty-year rotations, because the growing stock is a less 
important part of the capital. 

(4) The rate varies in narrow limits for all reasonable rotations and is 
little afifected by current expenses, 

(5) The rate does not materially vary with changes in stumpage value 
because capital and income are affected in like manner. 

(6) Extensive forestry with small expenses and small incomes yields 
practically as good a per cent as intensive forestry. 

(7) It is very doubtful if any business rate over four per cent should be 
used in forest investments (pre-war conditions). 

According to the figures cited by Roth, the per cent yielded by pine, spruce, 
oak, and beech, under ordinary rotations on four different sites of soil, is 
shown in the following table : 

Table 3. Rate of Interest Earned in European Forestry. 



Site Class 


Pine 


Spruce 1 


Oak 


Beech 


Oak — 160-year 
rotation 


I 


2.2 


2.5 1 


3.6 


2.9 


2.2 


II 


2.1 


2.6 


3- 


2.9 


2.1 


III 


2. 


2.6 1 


3-3 


3-1 


2.1 


IV 


2. 


2.7 j 




3. 


•• 



It is clear that the equality of the soil does not materially affect the rate 
of interest earned. The inference that may be drawn from these figures is 
that the rate used for compound interest calculations should be from 2 to 3%, 
but there must be periods, such as during 1914 to say 1930, when such 
rates appear low. But most calculations lead to false conclusions if high 
rates of interest are employed; any rate over 3^^% is doubtful. The length 
of the rotation is the crucial point. 

54. (b) What is Influence of Final Yield? The final yield is next in 
importance. Quality increment of course increases the value of the final 
yield and hence lengthens the financial rotation. 

Because of the lack of yield data and reliable stock figures and statistics 
upon which to base calculations, the tendency (in American Forest Regu- 
lation) has of necessity been to ignore the need for computing financial 
rotations. For this reason a synopsis of what Endres says on the subject 
of financial rotations is given (in fine print, appendix A (b) ). 



* Roth. P., "Business Rate of Interest and Rate Made by the Forest." (Forestry 
Quarterly, Vol. 14, 1916, page 258.) 



4^ American Forest Regulation 

55. Illustrations of American Attempts at Calculating Maximum Soil Rent Rota- 
tions. One of the earliest intelligent discussions of rotation (with a financial view- 
point) found in American forest literature is by Allen in the western hemlock.* 

In reply to the question, "At what age can the second growth stand be most profitably 
logged and how can the forest be perpetuated?" he showed that small size material 
"may be cut in 40 years and that in 50 years logs will be produced which would be con- 
sidered a fair size in the East today." Analyzing the mean annual growth, Allen says 
that at 50 years 40 board feet per acre per year could be produced; at 60 years, 366 
board feet; at 70 years, 471; and at 80 years, 500; i.e., the economic rotation already dis- 
cussed. His conclusion was that "it appears, therefore, that the greatest production of 
wood can be secured by cutting second growth hemlock when it is about 80 years old." 
He admitted that other points should weigh in forming a correct conclusion, such as 
natural regeneration, quality of material and net financial profit. He stated that "the 
rotation of greatest financial profit still remains to be reckoned .... the calculation 
can only be tentative." but he concludes that 70 years is the most profitable financial 
rotation and that wath $1.00 stumpage per thousand feet, the investment would yield 
414% compound interest yet we must be cautious of advising too short rotations, for 
building timber is what the world needs. 

In an early state** report the conclusion was reached that, 

"Whenever this interest (in the financial yield table) falls below the rate which may 
be earned by the money into which the timber can be converted, the forest should be 
cut." 

The authors conclude that the lower the rate used in the calculation of compound 
interest, the longer the timber may be left standing. With 4% interest and 
no quality increase, the time to cut any stand would be hastened ten years. This table, 
however, simply indicates the maximum age at which cutting should take place and 
does not determine the exact time to cut, because to answer the second question, we 
must know the items entering into the cost of production. With compound interest 
at 4% it was found that for white pine in New Hampshire the net profit would be the 
greatest between 50 and 60 3'ears of age — with land valued at $5.00, cost of planting at 
$7.00, protection at 10 cents per acre per year, and current local tax rates on the timber 
and on the land. In addition to paying 4% on the money with a rotation of 55 years 
there would be a surplus of $71.26, or an additional profit of $1.29 per acre per year. 

Frothingham's conclusions in regard to white pine rotations agree in the main with 
those (of the New Hampshire report) cited above, and he also agrees that the lower 
the interest rate, the later the financial maturity will occur. W^ith 4% interest the 
owner can afiford to hold the stand until it is 50 years old. If 6% interest is charged, 
the rotation must be reduced to from 40 to 50 years or a loss will ensue. He is correct 
in concluding that financial maturity does not coincide with volume maturity, because 
the mean annual growth in board feet culminated on site (I), at 60 years of age; on 
site (II), at 75 years; on site (HI), at 90 years. As Frothingham points out, seed years 
occur every 3 to 7 years, and if the stand is to be reproduced by natural means, it must 
be cut during a seed year. Therefore, it could rarely be cut precisely when financially 
mature***; this only serves to illustrate that rotation should be gauged by decades 
rather than by individual years, and that the final decision must be based on a number of 
considerations. 



*Allen, E. T., Western Hemlock (Bureau of Forestry Bulletin 1902. pp. 44-48)- 
** Forestry Commission of New Flampshire. 1905-06. p. 240. Reference is made to 
table 21. 

*** Frothingham. E. H.. White Pine under Forest Management (Forest Service Bulle- 
tin 13, 1914, p. 36, special reference being made to tables 12 to 17, which deserve careful 
study). 



Financial Rotations 47 

Ashe* defines rotation as "the most profitable age and size at which to cut," and 
analyses the rotation for loblolly pine in North Carolina, according to whether the 
tree is in mixed or pure even-aged stands. In these mixed stands the "most profitable 
trees to cut can be determined by the rate with (at) which they increase in value." On 
the basis of these single trees the author argues that "when the rate of increase in 
value declines to 6%, the tree can be considered financially mature." In other words, 
his argument was based not on an investment per acre, but on the current income value 
of the tree, his conclusion being: 

"Trees should be cut, therefore, when they are between 14 and 15 inches in diameter, 
breast high, at which size their rate of increase in value (neglecting increase in price) 
becomes equal to the current interest rate." 

With pure even-aged stands grown for sawtimber, the most important consideration, 
according to Ashe, is the "largest average per cent of (net) profit," taking into con- 
sideration soil value, interest, taxes and administration, or in other words, the cost of 
production. The author admits that the expense of growing timber is variable, but in 
the calculations made, assumes a soil value of $5.00 an acre and 6% interest. The 
increase in soil value and stumpage value, he says, "will in part cover the cost of pro- 
tection and taxes," but to be on the safe side, 1% should be deducted from the profit 
to cover taxes, protection and administration for the growing period, and he further 
contends that, 

"Since there is no cost of stocking other than protection and leaving seed trees, the 
initial investment is practically limited to the soil value. The growth of the seed trees, 
if they are carefully s^elected, should approximately cover the interest on the initial 
value." 

This is illustrated in the following table: 

Table 4. Value of Fully Stocked Stands of Loblolly Pine, as Scaled by Doyle-Scribner 
Rule, at Dififerent Ages on Different Quality Sites and Under Different Costs of 
Operation; and the Per Cent of Interest on an Initial Investment of $5 an Acre 
Represented by This Value. 

Quality I 







Rate of 




Rate of 




Rate of 






compound 




compound 




compound 






interest 




interest 




interest 


Age of 


Operating 


on an 


Operating 


on an 


Operating 


on an 


stand 


expenses 


investment 


expenses 


investment 


expenses 


investment 




$11 


of $5 an 


$13 


of $5 an 


$15 


of $5 an 


Years 




acre 
Per cent 




acre 
Per cent 




acre 
Per cent 


25 


$ 33 


8 


$ 18 


6.1 


$ 4 




30 


74 


9 


42 


7.0 


ID 


4.0 


40 


143 


8 


87 


8.0 


30 


5.0 


50 


231 


7 


158 


7.0 


84 


6.0 


60 


326 


7 


243 


6.5 


IS9 


6.0 


70 


423 




336 


6.1 


249 


4.5 


80 


496 




406 




316 




Quality II 


25 


$ 6 


0.8 


$ 3 




$ I 




30 


31 


6.0 


17 


5-0 


3 




40 


80 


7.0 


47 


6.0 


14 


30 


SO 


132 


6.5 


84 


6.0 


37 


4-5 


60 


193 


6.3 


136 


S-S 


80 


S-O 


70 


267 




206 




14s 


5-0 


80 


325 




261 




196 


4-S 

















* Ashe, W. W., Loblolly or North Carolina Pine (North Carolina Geological Survey, 
Bulletin 24, 1915, pp. 135-137). It must be admitted that timber production will rarely 
yield as high as 6% unless there are considerable stumpage increases. 



48 American forest Regulation 

Quality III 



25 

30 

40 














$ 27 


4.0 


$ 15 




$ 3 




50 


61 


5.0 


36 


4.0 


u 




60 


97 


4-5 


65 


4.5 


2,2 


3-5 


70 


141 




103 


4-5 


65 


4.0 


80 


177 




137 


4.0 


97 


4.0 



Different results would have been secured had the yield been based on mill run. 
The conclusion was reached that the less favorable the quality site the later is the age 
at which the maximum interest rate is attained; this agrees with the conclusion of 
European foresters. For pure even-aged stands of cordwood there is little, if any, 
increase in price with increase in size. Therefore, the volume of the stand and the cost 
of production are the proper bases for the rotation. 

"The cheapest cost on all quality sites is when the stand is between 

25 and 30 years old." Such short rotations are often veritable nonsense. 

The conclusions on the cost of growing cordwood are illustrated by the following 
table: 

Table 5. Cost of Growing Cordwood in Fully Stocked Stands of Loblolly Pine at 
Different Ages on Different Quality Sites on Land Valued at $5 an Acre and 
Interest at Six Per Cent. 

Stem Wood Only from Trees Six Inches and Over in Diameter. 



Value of $5 Cost of growing a cord of Cost of growing a standard cord 

Age of compounded at 160 cubic feet, peeled of 128 cubic feet, bark included 
stand (i% for the 

period, less Quality Quality 
Years tlie initial 

investment I II III I II III 



25 


$16.45 


$0.50 


$0.74 


$1^37 


$0.26 


$0.41 


$0^75 


30 


23-65 


■55 


•70 


I-3I 


•31 


•44 


•71 


40 


56.40 


•97 


1^34 


2.02 


•59 


•78 


i^i3 


50 


87.10 






2.49 


•83 


1.05 


1.45 



According to Stcrrett's investigations* on the ash, 

"The financial rotation is lengthened by low yields, low stumpage values, and high 
initial investments, while the opposite of these shorten it." 

It was argued that financial rotations may be altered according to the purposes for 
which the timber is grown; according to market conditions and seed year occurrence. 
From the silvicultural viewpoint short rotations are best, and long rotations in pure 
stands should be practiced only on the best sites, and then the ash should be usually 
underplanted. Rotations of 30 to 60 years are recommended. 
Special reference is made to table 6, which follows: 



* Sterrett, W. F., The Ash's, Their Characteristics and Management. (Forest Service 
Bulletin 299, 1915, pp. 35-39.) The costs of the crop Vo X i.op° = value of the crop in 
n years (Vn). When the costs of the crop is less as in poorer quality sites n must be 
greater where p is constant. See Chapman's Valuation. It should be noted that 6% 
interest rates in forestry calculations arc rarely possible or advisable. 



Financial Rotations 49 

Table 6. Interest rates' (compound) to be expected on money invested in growing 
ash, where yield quality I. 11, or III stands are secured, calculated for different 
stumpage values and for different initial investments. 

(Blank spaces mdicate less than 3 per cent interest.) 





h. 














Total initial investment 


per acre. 












"B 
































S 


3 
« - '' 




$5.=' 






$I0.« 






$is.* 


? 


20.5 




$2S-« 




$3 


oJ 


(0 »>. 


*♦* L- 
































~ii 


2. tj 




Compou 


nd interest 


rates 


; (per 


cent) for 


yield 


quality I, II, 


and 


III 


stands. 




< 


> " 


I 


II 


III 


I 


II 


III 


I II III 


I II III 


I 


11 


111 


I 


II III 


20 


$ S 
10 
IS 
20 


4.2 
7-S 
9.6 
II. I 






3.9 
5-9 
7-3 






4-3 
5.6 




4-1 




3-3 




















30 


5 
10 


6.1 
8.8 


4.6 




3-7 
6.3 






4-9 




3-9 




3-2 












IS 


10.3 


6.2 




7.8 


3-7 




6.4 




5-4 




4.6 






4.0 






20 


11.4 


7-3 




8.8 


4.8 




7-4 


3-S -- 


6.4 




5-6 






5-0 




40 


5 


.S.8 






4.0 














3"-6 












10 


7-9 


S-5 




6.1 


3-7 




S-o 




4.2 








3-1 






15 


9-1 


6.8 




7-3 


4-9 




6.1 


3-8 -. 


5-4 


3.0 


4-7 






4-3 






20 


lO.O 


7-7 




8.1 


5.8 




7.0 


4.7 . . 


6.2 


3-9 


5-6 


3-3 




S.I 




=;o 


S 


5-3 


3.3 




3.8 


























10 


7-1 


S.6 




S.b 


4.1 




4.7 




4.1 




3-S 






3-1 


. . 




IS 


8.1 


6.6 


3-9 


6.6 


S-2 




5-7 


4.2 . . 


S-i 


3-6 .. 


4-5 






4.1 


. . 




20 


8.8 


7-4 


4-9 


7-3 


5-9 


3-4 


6.4 


4-9 - - 


5-7 


4-3 


5-2 


3-7 




4.8 


3.3 


60 


5 
10 


4-7 
6.4 


3-0 
5-3 




3-S 

S-2 


4.1 




4-3 




3-8 




3-2 












IS 


7-3 


6.2 


4.4 


6.0 


5-0 


3-2 


S-2 


4.1 - - 


4-7 


3.6 .. 


4-2 






3-9 






20 


7.8 


6.8 


5-2 


6.6 


S.6 


4.0 


5.8 


4.8 .. 


5-3 


4-3 


4-8 


3-7 




, 4-6 


3-4 


70 


5 
10 


3-9 
6.4 


4.8 




il 


.3.8 




3-7 




3-3 
















IS 


6.S 


5-7 


4-4 


.S-4 


4-7 


3-4 


4.0 


3.8 .. 


4-- 


3-4 


3-7 






■ 3-4 






20 


7.0 


6.3 


■S-l 


5-9 


5-3 


4.1 


S-2 


4-S -- 


4.8 


4.0 


4-3 


3-5 




. 4.0 


3-2 


80 


s 

10 


4.S 


3-9 




3.9 


3-0 
























13 


5-0 


S-o 


3.8 


4-7 


4.1 




3-9 


3-1 - - 


3-5 
















20 


6.1 


5-7 


4-7 


5-2 


4-7 




4-S 


3.8 -- 


4-1 


3-5 


3-6 






• 3.4 


. . 





































> Calculated by the formula p = 100 [V p_j_^^ ']. where p = compound interest rate, n = number of 

years or rotation, S = stumpage value at n years; L = cost of land; F = cost of formation; and A ^ 
cost of administration and taxes in n years at 6 per cent compound interest. Five cents per acre annually 
is allowed for administration (including fire protection) and one cent on the dollar {full valuation) annually 
for taxes. 

' $5 cost of land, and no cost of formation of stand. 

s$s cost of land, and $5 cost of formation of stand. Nqte. As a matter of fact calculations such as 

*$io cost of land, and $5 cost of formation of stand. ^v c^ ■ 1 j- 

s $10 cost of land, and $io cost of formation of stand. t^"« ^'''^ "^'^^ misleading. 

" $15 cost of land, and $10 cost of formation of stand. 

^ $15 cost of land, and $15 cost of formation of stand. 

The Forest Service has used this method of indicating the most profitable rotation 
on the assumption that money must be borrowed at 6%. At best it is an approximation 
because it is difficult to answer the financial rotation problem in advance with so many 
dependent variables. According to the formula used, the equation would work out for 
50 years as follows: 



(V^ 



... , .-,/ $99 + $5 - $29.04 ,.-^w ..^-.- 0/ 



Here the value of the land i$ added at 50 years as it is assumed still to be worth $5.00. 
Table 7, which follows, illustrates a method of determining the financial rotations* 
for eastern white pine in common use in the United States. In this case the most 
profitable rotation is 50 years and the result is more exact, according to the soil rent 
theory, than in the preceding equation. 



* Forest Mensuration of the White Pine in Massachusetts, 191 1. (State Forester, 
Boston, p. 26.) 



so 



American forest Regulation 



Table 7. The Financial Rotation of White Pine. 
(JMoncy valued at 4 per cent; value of land, $4 per acre; cost of planting, $10 per acre.) 









EXPENSES AND INTEREST. 















2 3 






Taxes. 






Cost of 

Producing. 


c ti 


rt „ 




h c . 


•<^ 

H to 

WW 

u 

< 


C/2 


^4 

•3 >>.2 
= n h 




ount paid - 
n Taxes. * 

W 

ccrued at 
Per Cent 
merest. 


ON 

3 M 

<u 

•5fc 
> c 


LAND. 




Coo 

rt " 
■"Mo 
C 3 


c *^ 
1-1 3 
» 

^1 


c ^ a 

o" 




u 
Cm 


u 



OS S 
Ph u > 






<'^" 




<; ^ 








u-b 




^< 






2.S 


$ 40.50 


$ 540 


$ 2.70 




$1.50 


$ 2.17 


$ 6.66 $ 26.66 $ 


11.50 


$ 35-49 


$ 29.00 


$ 5-01 


30 


75.00 


1,000 


2.70 


$ 3.03 


1.80 


2.90 


8.97 


32.43 


14.50 


47-33 


60.50 


27.67 


3.S 


195.20 


1,269 


7.70 


9.32 


2.10 


3.82 


11.78 


39.46 


19.80 


64.38 


175.40 


130.92 


40 


262.40 


3,498 


14.04 


18.47 


2.40 


4.92 


15.20 


48.00 


26.40 


86.59 


230.00 


175.80 


4,S 


324.80 


4,330 


31-53 


42.16 


2.70 


6.25 


19.36 


58.41 


44-23 


126.18 


280.57 


198.62 


.■^o 


465.00 


6,200 


53-18 


75.76 


300 


7-90 


24-43 


71.06 


66.18 


179-15 


398.82 


285.85 


5,S 


505-50 


6,740 


84-18 


127.04 


3-30 


9-90 


30.58 


86.46 


97.48 


253-98 


408.00 


251.02 


60 


532.00 


7,080 


117.88 


192.60 


3.60 


11-35 


38.08 


100.79 


121.48 


342.82 


410.52 


189.18 


65 


566.00 


7,54« 


153-28 


281.32 


3-90 


i5-i8 


47-20 


127.98 


163.28 


471.68 


402.72 


94-32 



According to Mattoon, the object of management with cypress should be "to secure 
the highest financial returns from the class of land involved .... and the continuous 
yield of the most valuable species." His conclusion is that a 60-year rotation (with 
the object of raising poles) would be the most profitable age at which to cut.* 

In a recent calculation for Douglas Fir, Quality II, Hanzlik indicates a 70-}'ear finan- 
cial rotation in the Western Cascades. 



-sSuiuuiqx 
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<u 


u 




Q ■'d 


< 





u 



> 


u 





-33JX a^BjaAy 


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z 


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2; 












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H 




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X 








W 








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paAouia^ saajx 'ON 


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H 









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s 


- 


z 












s 




- 


z 












8 






8 


8 












(N 


tx 


00 


CTi 















cq 


s 

































to 



of 





8 














= 


fe 
















= 


cd 



































0) 
0< 




C30 




0^ 


C5 


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1 


f 







01 


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-r 


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ir; 


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* Mattoon, W. R., The Southern Cypress (Forest Service Bulletin, No. 272, 1915, p. 50). 



Financial Rotations 



51 



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Based on present National Forest Practice and Sales Regulations in Douglas Fir Region. 
D-6. 

Cost of Formation — nil. Computed by E. J. Hanzlik, U. S. Forest Service. 

Annual expenses — .20 per Acre. Data based on Standard Douglas Fir Yield Tables ; 

Interest — 3% per Annum (comp.). Ms. report by E. J. Hanzlik, U. S. Forest Service. 
Tax on Yield— 35% of Gross Receipts.Rev. in Forestry Quarterly, Vol. XII, No. 3, pp. 440-51. 

o _ Yr + TaXl.op'" — ^+ . • • Tq X 1- op'" — q — C X 1- opr 

l.opr — 1 ~^ 

56. Final Choice of a Rotation. The object of the owner will always be 
the principal factor in the choice of a rotation. This object may vary some- 
what according to whether the owner is a state, a company, or an individual. 



* Financial Rotation indicated at 70 yrs. 



52 Aincricaii Vorcst Regulation | 

The length of the rotation will depend also on whether this principal object 
of management is the direct production of timber or the indirect benefits 
of the use of the forest for recreation or watershed protection. Since the 
use of aeroplanes has become so general in war, the French attach consider- 
able importance to the value of frontier forests as a screen to the movement 
of troops. This is but an illustration of the indirect protective ^■alue of 
forests which under exceptional circumstances would influence the choice of 
a rotation and system of cutting. It is safe to lay down as a general rule 
that where the indirect benefits of forests are of greater moment with the 
owner than the mere production of timber, the rotation is usually lengthened. 
In a forest park such as Fontainbleau, near Paris, or in the famous Wiener- 
wald near Vienna, the rotation would be longer than a sound technique would 
permit were the production of timber the sole object. So-called protection 
forests on the slopes of mountains usually have their rotations lengthened 
through the mere fact of being managed for protection purposes, aside from 
the slow growth due to soil or exposure. The silvicultural treatment to be 
followed has an important bearing; sometimes this is the dominant factor 
as in the case of a simple coppice of oak where the sprouting capacity fails 
rapidly after 50 or 60 years. With naturally regenerated oak high forest a 
maximum limit may be set to the length of rotation because of the falling 
oflf in seed production. But if the main object of management is timber pro- 
duction, a rotation based on the maximum income in wood material is indi- 
cated if this coincides with the (forest rent) financial rotation. If the two 
do not coincide as seldom happens, then a compromise must be made by 
the owner on the basis of the best available data. According to Schlich,* 

"In the first place, the financial (soil rent) rotation should be determined as it alone 
gives a true expression of the economic value of the management; then, it should be 
ascertained in how far the objects of management demand a departure from the financial 
rotation; lastly, the financial loss involved in such a departure should be determined, 
so that the proprietor may have a clear conception of the payment which he is called 
upon to make in order to realize his special object." 

As Schlich well points out, the drawbacks to purely financial rotations in 
impoverishing the soil must be borne in mind. Quantitative (economic) and 
financial rotations (which have been discussed at length) depend on more 
complete yield and market data than is usually obtainable during the initial 
stages of forest management. It is for this reason that this type of rotation 
has often been replaced in the United States by tentative technical or silvi- 
cultural rotations; an authority such as Endres** refers to these latter rota- 
tions as being of mere "historical interest" because of the development in 
Germany of detailed yield and market data. 

57. Summary of Principles Affecting Length of Rotations. Let us now 
summarize some of the principles upon which the determination of the rota- 
tion depends : 



* Schlich, William, Manual of Forestry, Vol. Ill, 191 1, p. 202. 

** Endres, Max, Lehrlnich der Waldivertrcclmung und Forstatik, 1895, PP- 220-248. 



Fiiiancial Rotations 53 

(i) The length of rotations tends to increase on poor sites and decrease 
on good sites. (Yet in North Germany there are short rotations on pure 
sand.) 

(2) In financial rotations (soil rent) the lower the interest rate, the 
longer the rotation allowed by the calculation, but other factors must be 
considered, 

(3) An increase in the quality of product yielded lengthens financial 
rotations. Quantitative rotations will vary according to the utilization in the 
tops, according to the log rule used, and according to the basic class of product 
(whether cubic, board feet, poles, ties, etc.), 

(4) When the mean annual growth begins to decrease, the per cent of rot 
increases ; danger from defect limits the length of rotation with such species 
as white fir. 

(5) Rotations vary according to the ownership and purpose, silvicultural 
treatment, market and logging conditions, site, species, as well as with the 
character and condition of the stand. We must never forget that the world 
needs building timber. 

(6) With more intensive economic conditions there is always a tendency 
to shorten rotations ; with extensive economic conditions longer rotations are 
indicated (with long cutting cycles). 

(7) In choosing a rotation technical, silvicultural, quantitative and financial 
considerations should be summarized before making the final decision. But 
the object of the owner must always have the dominant interest in deciding 
upon what rotation to choose. 

(8) Once a preliminary rotation has been established, modifications are 
necessary with economic changes. 

In the United States Roth advocates a rotation no longer than necessary 
to produce the kind of material desired and a reasonable income as well as to 
maintain the fertility of the land. He believes in calculations to show the 
highest net financial (forest rent) yield. He correctly emphasizes that in the 
future, market sizes will be smaller and rotations will be reduced by thinnings 
and by efficient planting. Roth also favors short rotations where open stands 
may otherwise suffer from insects and fungus.* 

** The author dismisses the rotation of maximum volume and the rotation of forest 
rent, the former based on false public economy, the latter because based on false mathe- 
matical basis; there remains for discussion only the rotation of maximum soil rent and 
the technical rotation, the latter being defined as that which produces continuously the 
largest quantity of the most valuable marketable wood under the given conditions of 
site and market. These two rotations are in many cases identical (coppice) .... 
The financial rotation depends in the first place on the choice of the rate per cent." 

Recknagel first divides the customary European rotations according to whether (i) 
small or (2) large tracts. The average rotation for small tracts (presumably intensive 
forestry) he shows is 10 to 20 years less than for large tracts. Then he distinguishes 
between (i) plains and foothills, (2) intermediate mountains, and (3) high mountains; 
and within each topographic subdivision a further differentiation by species. But these 
data are not of real scientific value because the basis for the rotation under the different 



* Roth, Filibert, Forest Regulation, 1914, p. 117. 

** Review by Fernow of article by Pilz (Forest Quarterly, Vol. 2, 1904, p. 183). 



54 American Forest Regulation 

conditions is not given. In the plains the rotation might be purely on the basis of soil 
rent while in the mountains perhaps soil protection was of paramount importance in 
determining when to cut. His averages for small tracts of spruce are (i) 60-80 years 
in the plains and foothills, (2) 60-100 in the intermediate mountains, and (3) 80-100 
years in the high mountains. Roth* says more specifically that the, 

"Rotation for largest volume in Germany and for fair to good site (site II) is about 
as follows: pine 60 years, spruce 90-100 years, l)eech and balsam 1 10-120 years. This fits 
in very nicely with the technical rotation for these species." 

The writer agrees thoroughly with SchifTel's conclusion that, 

"Today we know that a careful survej^ and critical investigation of stands as regards 
their silvicultural condition, a comparative observation of their development, and the 
proper selection and attention to their growth of species furnishes a much surer basis for 
securing maximum revenue than Pressler's formula receipts." 

Yet especially in American Forest Management, a forester cannot adopt 
ideal methods, but must weigh the results with the cost. An ideal might be 
to have complete fire protection, but the ideal may be shattered by considera- 
tions of cost. Will it pay?** must be answered before regulation measures 
are finally decided upon. 

It is too early to try to average or classify rotations established in the 
United States. In the majority of cases they have not been tried out so that 
they are purely theoretical rather than empirical. Extensive forestry means 
much longer rotations than will prevail later on because of the extensive 
conditions sufficient differentiation has not been made. With a possible 
shortage in the world's timber supply, short quantitative rotations for maxi- 
mum production are predicted; and quite probably in the tropics under 
favorable growing conditions the rotations may be one-half to one-third those 
required in the temperate zone. 

58. Quiz. Define the maximum forest rent rotation. 

Review definitions of capital and value. 

Write and explain the forest rent formula. 

How does it differ essentially from maximum soil rent? from economic rotation? 

Under what conditions are soil rent rotations preferable? 

Why is the answer based on mean annual rather than current annual maxima? 

Is this rotation applicable to national forests? to woodlots in New England? to the 
southern pineries? 

What are the difficulties to its wider use? 

How would the rotation be affected by the omission of thinnings? by heavy inter- 
mediate returns? by natural regeneration? by heavy forestation expenses? 

How do large soil values aflfect the result? 

How does price increment and quality increment affect the result? 

Write and explain the soil rent formula. 

How do you arrive at the culmination of a forest rent and soil rent rotation for given 
conditions? 

Give a simplified form of the soil rent formula. 

How important is the rate of interest used? 



* Review by Fernow of article by Schiffel entitled Rev. Reinertragslehre in der Gegen- 
work, G. A. Schiffel (Forestry Quarterly, Vol. 2, 1904, p. 186). 

** Recknagel, A. B., Certain Limitations of Forest Management (P. S. A. F. Vol. 8, 
1912, p. 227). Recknagel has done a great deal for American Forest Management by 
publishing widely on technical forestry, much of it from reliable German sources. 



Financial Rotations 55 

What rate should be chosen? 

Of what importance is the final yield upon the result? (The study of the translation 
from Endres may be made optional.) 

Comment on illustrations of financial rotations established in the United States. 

What should be the chief factor in the choice of a rotation? 

Discuss the choice of a rotation. 

What are some rotation variables and axioms? 

Cite some rotations established in Europe. 

Contrast these with those suggested for the United States. 

The student should be given rotation problems to work out in order to fix in his mind 
the relative length of rotations for given conditions according to whether they are 
physical, economic, etc. 



CHAPTER VI 
THE NORMAL FOREST 

59. Definitions of Normal Forest, Normal Increment. — Normal Forest — 
A standard ivith ivhich to compare an actual forest to bring out its deficiencies for 
sustained yield management ; the conception of an ideally regulated or organised 
forest; a forest with normal increment, normal age classes in sice and distribu- 
tion, and normal stock. 

Normal Increment — The best increment attainable by given species on given 
sites. 

Normal Age Classes — The presence of a complete series of age classes as will 
permit annual or periodic fellings to be made. 

Normal Growing Stock or Normal Stock — The amount of material repre- 
sented by the stands m a normal forest ; practically, the contents of the normal 
age classes as represented in normal yield tables. 

The equalisation period is the period during ivhich it is planned to attain approx- 
imately normal stock conditions. (G., Einrichtungszeitraum.) 

60. Discussion of the Normal Forest. The difference between the nor- 
mality of the normal forest and that of the normal yield table must be clearly 
understood. The normal forest is merely an ideal difficult to attain, while the 
yield of the normal yield table is ahvays attainable since it is based upon the 
averages of actual measured stands. Even such a forest as the Sihlwald 
(cited by Roth) falls far short of being normal even from the sole viewpoint 
of normal age class distribution. Nevertheless the normal forest will always 
prove of value as a basis for comparison. 

The normal forest requires : 

(i) A normal distribution of age classes and a complete cutting series 
which usually leads to : 

(2) A normal increment. 

(3) A normal growing stock. 

These have already been defined and will be discussed in detail later on. 

A forest may be referred to as under-stocked zvhen it has a growing stock 
less than the normal grozving stock; or overstocked zvhen it has a grozving stock 
greater than the normal grozvi)ig stock. 

61. Three Phases of Abnormality. As a matter of fact, forests are usually 
abnormal in three ways : 

(i) Over-stocked. A forest past the age of maturity may have more 
volume per acre than the normal. Therefore, there will be surplus 
growing stock which must gradually be removed. This surplus may be 
because there are too many acres of the older age classes (see # 3 below). 

(2) . Under-stocked. The increment may be more than the average, but 
the growing stock, because there is too large an acreage in immature stands, 
will be less than normal. Consequently, the forester may be called upon 
to economize by cutting less than the increment to accumulate a proper 



The Normal Forest 57 

reserve growing stock. This is particularly true where the yield must be 
cut in board feet for sawmill purposes, because lumbering trees less than a 
certain size is usually uneconomic. The accumulation of growing stock to 
remedy a deficit is often secured by adopting a rotation that is more than 
the time required to grow the stand or by cutting less than the estimated 
sustained yield. 

(3) Vohunes Nor^nal, hut Age Classes Abnormal. This is the worst form 
of abnormality because the entire forest may be practically of one age class 
(the reader should conceive of one age class as allowing a variation of 20 
years). This is especially unfortunate because it will necessitate such a long 
delay before lumbering can take place again. It precludes the maintenance 
of a sustained yield. It represents the probable situation in the United States 
when our virgin timl^er is exhausted by destructive logging. 

62. A Normal Distribution of Age Classes. This requires that separate 
age classes exist which will mature during each year or period of the rotation. 
These age classes must occupy areas whose yield will equal the same relative 
per cent of the total yield of the working group for the entire rotation that 
the year or period bears to the rotation. In theory each of these age classes 
must occupy areas of equal productiveness so that if they are cut at the 
proper age, equal annual or periodic yields are obtained. The basis for com- 
parison is the yield from yield tables. If one acre of a forest yields 50,000 
board feet at 100 years while another yields but 25,000 then there must be 
two acres of the latter for every acre of the former in order to have a normal 
age class distribution. Where the increment of a forest with normal age 
classes is only half what it should be, its age class form would be normal 
and it might have a sustained yield because the beneficial results of a sus- 
tained yield are not wholly dependent on full increment per acre but on well 
distributed age classes. 

63. Artificial and Natural Factors Influencing Distribution of Age Classes. 
Unfortunately an abnormal distribution of age classes is the rule because of 
artificial and natural factors. The artificial factors are : 

(i) A full cutting series is required. A cutting series is an aggregation 
of compartments (stands) in a proposed or actual sequence of cutting areas, the 
object being a distribution of cutting areas for administrative reasons, or to 
secure a final satisfactory distribution or location of age classes, especially 
to avoid damage by windfall and insects due to uniformity of stand and size 
of cutting area. It is therefore intended to interrupt a regular sequence of 
age classes. 

(2) The number of age classes hinges on the number of years in each 
age class (usually 20 years) and on the length of rotation adopted. If the 
rotation is changed, the number of age classes required is modified, and the 
forest which was normal in this respect for one rotation becomes abnormal 
for the next. 

(3) The area proper for each age class depends directly upon the total 
area in the working group and on the rotation and number of age classes. 
Consequently, areas which are normal for one rotation become at once too 
large if the rotation is lengthened or too small if it is shortened. 



58 American Forest Regulation 

The natural factors are even more perplexing-. There are always too large 
or too small areas or volumes present, requiring increases or reductions in 
given age classes. It is for this reason that the minimum time required for 
the transformation of a forest to normal age classes is one full rotation, and 
practical considerations usually call for at least two rotations or more. But 
as a matter of fact, the ideal is seldom, if ever, attained in age class distribu- 
tion, but if it is attained and the rotation is modified because of economic 
conditions, the process of regulation must start over again. Accidents, such 
as windfall, fire or unusual local demands which must be met, are continually 
delaying transft)rmation to more normal conditions. 

64. Normal Increment. The second requirement of a normal forest is 
normal increment. It is theoretically normal if there is maximum growth on 
all parts of the area for given species and sites. It is the goal of silvicultural 
practice. Just as in the case of age class distribution, normal increment can- 
not be attained until the second rotation, and not even then unless perfect 
success has been obtained throughout the first rotation — something that is 
entirely impossible. Normal increment does not serve as the basis for the 
regulation of the cut in the first rotation, since in this case actual increment 
is used as a base because normal increment would not apply. Actual incre- 
ment of normal or ideal stands, or even the average for the stands 
that are fully stocked, according to local or general yield tables, does not give 
the forester an idea of the growth on excess stands. The increment on 
existing stands must be determined in each case, and any attempt to regulate 
the cut, (based on the removal of surplus growing stock or on enriching the 
forest where the growing stock is deficient,) must be based on the study of 
the actual increment and not on the theoretically normal increment. 

65. Normal Growing Stock. The third criterion of normality, normal 
grozvi)ig stock, might be actually attained. But nevertheless it is simply an 
ideal, which unfortunately is often misunderstood. One writer contended 
that our knowledge of the forest is so indefinite and the irregularities so 
unending that a normal condition cannot be conceived, and that normal stock 
is therefore a delusion.* Often a forest may falsely appear to have a normal 
stock owing to an accumulation of volume in stands past the rotation age; 
this phase of abnormality must be recognized especially when a very short 
rotation has been chosen. 

There is nothing in this argument to justify throwing overboard the idea 
of normal growing stock. It only serves to emphasize the need for bearing 
in mind that normal growing stock is an ideal to steer by. 

The length of rotation is especially important in affecting the normal 
growing stock, where the forest is to be managed on the basis of permanent 
production. This is true because the rotation, 

(i) Determines the amount of timber that must exist as forest capital in 
order to obtain a continuous yield ; and 

(2) Indicates whether a surplus or deficit exists in the actual forest under 



* Review by Fernow, entitled Heresies Regarding Normal Stock. (Forestry Quar- 
terly, Vol. 14, 1916, pp. 524, 553-67.) 



The Normal Forest 



59 



management and tells whether more or less than the actual increment can 
be cut. 

66. Growing Stock Formulae, To obtain a clearer conception of the 
normal forest and its normal growing stock reference is made to figure 3. 



'""" x : 




_i_ _i_ 




1 










- ^ =^ 


; 


t ^^ 


~r 


-4 ^^ 


1750 


- / N. 




t N 




it -4 '^^ 




/ ^>^c 




L sc - 




ZL it i ^ . 




/ ^ ± ^ 




t -t 


J 


7 ^ 


i 


t \ 




-. \ 




1 5 




t 5 








2 5 


I2S0 


t % 








7 ± X 




z: s 








1 


1 


t 


J. i 










-■I -=-"$ -a- ^'''^ 


' 


/ ^^ :^^2 


' 




1 


/ t -^^^ --^'^ 




J X- ^^^ 


; 1 


V v^ -^ 


7\>0 1 ' 1 


Zt ^'^ ^"^ 


1 i 


^ ^^ ^ ^^ 




Z -,^ -=•" 


1 ; 


^ ^^ ^^ ^ " 




Z J^ -r^ '^ 




^ ^^-^ 




IZ z^ y 




X ^^ ^ 




^ ^^^ -fc 




^ ^^^^ ^^ 




t ^^ ^ 


• 


'^ ^ ^ . 


1 


? ^^ ^ 


± - -^ ' 


^^^ 


4^T; -=" ^ 


^^ / 


250 ^-^ U 


■^ 7 


^^ 




^'' y 


-^ 


^■^ ^^ 




^ ^ 




^ ^^ '-'" 




■^ '^ 




^ <^ '^y' n ^ 




0^ to lo 


30 • AO 30 & 










\ 51. N] T 


AAS v^MD ^.Ct^o^Gil- N *>C>.LS. | 


«. 0^ «, 








1 ' 




1 I 




I 




L 


± _ .. _ ± 



Fig. 3. Diagrammatic Representation of Normal Growing Stock 
Annual and Current Growth for a 60-year-old Stand S 



and a Comparison with Mean 
ixty Acres in Area. 



A forest of 60 acres is here represented as being managed on a rotation 
of 60 years. If the entire forest were very abnormal and contained 60 acres 
of mature timber, then the volume would be represented by the diagram 
a-b-d-e. But let us suppose it is normal. Then there will be one acre one 
year old, one acre two years old, one acre 59 years old, and one acre 



6o American I'orcst Regulation 

60 years old, or about half what the forest would contain if it consisted entirely 

uf fully mature stands. The column b' represents graphically 60 years growth 

and the column at the extreme left of the triangle represents one year's 

growth. From this it is clear that a simple formula for normal growing 

r V i 
stock is as follows : G" = rotation X m. a. i. -^ 2 or G" — — ^— 

2 
It is customary to ignore the effect of thinnings on the equation. 

This formula falsely assumes that current annual growth and mean annual 
growth remain ecjual. The author obviously overlooked the fact that growth 
is not laid on in annually equal quantities, but that it varies according to 
the age of the tree. The fallacy lies in the assumption that current growth 
and mean annual growth are the same for all ages. As a result of this false 
premise, if most of the growth is laid on in the latter half of the rotation, 
the actual growing stock required is less than that given by the formula, 
because the mean annual growth or proportional volume is less for the 
younger age classes. This is particularly true when the growing stock is 
measured in manufactured products, where it is almost universal that a tree has 
no measurable volume in board feet until it is 15, 20, or more years in age. 

This fallacy of assuming that growth is a straight line is shown diagram- 

matically in fig. 3, where a-cm-ccc-b represents current growth and 

a-cm-mmm-b the mean annual growth according to table 8. To correct 

this inaccuracy of assuming the growth a straight line ab, Moore* (P. S. A. F., 

Vol., VII, 1912, pp. 15-16) originated a formula which is a makeshift plan 

based on the disadvantage of the board foot rule but unquestionably it gives 

r V i 

more conservati\e results in the United States than the formula ^ — • His 

2 

r' X i 

formula is , where r' is the rotation minus the age when the tree becomes 

2 ^ 

merchantable. In this case the tree would be (see line fb, fig. 3) merchantable 
at 15 years or half way between 10, when the yield is o, and 20, when the 
yield is 4500 (see table 8). 

The use of this formula Moore claims will give a more correct surplus 
or deficit when compared with the actual stock which includes only the 
merchantable trees. He states that, 

"Where the increment is known to be too low, it is unwise to try to correct the 
error by using r (the whole rotation) instead of r' (the difference between the age of 
the merchantable trees and the rotation). The whole rotation wnll give a growing stock 
which is actually more correct, but mathematicallj^ incorrect and hence uncertain; it 
may be too large or too small. It will also give too low a cut of increment in the final 
formula and will not be counterbalanced by a high surplus." 

While Moore's argument is sound his substitute formula according to M. 
H. Wolff is incorrect. The proof of this, and the correct formula, are best 
developed graphically. 



* See Schlich's Manual of Forestry, Vol. Ill, 1911, pp. 222-227. In intensive forestry 
it would make a difference in the amount of the normal stock whether it were calculated 
in spring before growth, in summer after growth, or in autumn after the years cut, but 
for American conditions this complication can safely be omitted and calculations may 
be standardized to correspond with tlie summer when the year's cut is half completed. 



The Normal Forest 



6i 




Fig. 3(a) Proof of Wolfif Formula. 



Assume the triangle DBC represents the total normal growing stock on any tract includ- 
ing all merchantable and unmerchantable (nonestimable) sized stands, DC being equal 
to the rotation age (r), and BC being equal to the mean annual increment (I) of the 
whole acreage. "V can be more definitely expressed as the mean annual increment 
per acre (i). times the rotation age (r) multiplied by the total acreage (A) divided 
by (r). 

I = (iXr)X '^. 

As'^ume also that DH represents the merchantable age (s), and that FH is the 
volume at that age (F) of the annual acreage to be cut over. Volumes below this age 
are not estimated. 



Moore recommends that properly, the normal stock should be figured as 1 



(r-s) 



in the figure above to 



BCXHC. 



Diagrammatically this is equal to the triangle BCH. 



This assumes that volumes at merchantable age commence at zero. 

But really the volume at the minimum estimateable age is appreciable. It is theo- 
retically the mean annual growth times the number of years. Thus in our figure the 
normal growing stock above merchantable age (call it GN for convenience) is the 
quadrilateral (A trapezoid) FB CH. Hence Moore's suggested formula excludes tri- 
angle FBH and gives by that much, too low a figure. 

To obtain the correct and most convenient formula for normal growing stock above 
merchantable age, it is necessary to find the value of the area FBCH, in terms of T, r, 
and s. 

I = BC; r = DC, and s = DH. 



(i) FBCH 



_FH + BC 



XHC 



= I>tI-Xr- 



(2) F:s::I:r; 

(3) Substituting for F in (i) 



F I ,, 

or = ; or 1 = 

s r 



+ 1 



FBCH 



2 
Is-t-Ir 



X (r — s) 



-Xfr-s) 



62 



American Forest Regulation 



I(s + r) (r — s) 
2r 



(4) 



I(r'-s') 



This is mathematically the correct formula to use, but see table 9. 

67. Illustration of Simplest Normal Growing Stock Calculations. The values result- 
ing Ijy tlie three different metliods in any example arc interesting to note. Assume 
r=:6o years, and S = i5 years (i.e., when tree becomes merchantable). Then by the 

(a) ordinary method: Gn=:^|"°(or i X 30; by (b) Moore'5 suggested method 

Gn= ~'^, or iX22.S; by the method (c) here recommended (after Wolff) 

Gn == I X ^°°": ^,^ , or i X 28.125. 
2(60) 

Assuming the mean annual increment at 60 years given in table 8, we have (see 
table 9): 

(a) ^ 003X60 ^ ^^^^^^ ^^^^ J, ^^ ^^^^ ^^^^ 
2 

Cb) 1003 X (60—15) = 22,567 feet B. M. 
2 

(c) 1003(60'— i5')„^ 28,209 feet B. M. 

\ 20 

68. Yield Table Method of Computing Growing Stock. None of these 
formulae are as accurate as the result obtained by adding yields from a yield 
table (see table 8) expressed as a formula; thus, 

f 
10 (a + b + c -f d + e + 2) 



=3 normal stock per acre, where a =: the yield 



at 10 rears, b at 20 years, etc. 



10 years 

0- 

0000 ft. 


20 years 

© 

4500 ft. 


30 years 

© 

13900 ft. 


40 years 

© 

32S00 ft. 


50 years 

© 

49T00 ft. 


60 years 

© 

6o2no ft. 



Fig. 4. Diagrammatic Scheme of the Yield Table Yields. 

Referring to Figure 4, let us conceive of our normal forest composed of 
six square areas, each 10 acres in extent; with the assumed rotation of 
60 years, each scjuare will then correspond to 10 years of the rotation. In 
computing the normal growing stock formula, it is clear that each yield 
figure from the normal yield table must be multiplied by 10 to secure the 
normal growing stock for a forest of 60 acres. Half the yield in square f 
is taken because cutting is going on in the oldest age classes; consequently 
all the timber will be standing the first of the decade but none of it at the 
expiration. 

69. Illustration of Calculating Normal Growing Stock from Yield Table. As an 
illustration of the calculation of normal growing stock by the yield table method, the 
following is given for site (I), white pine in New Hampshire managed on a rotation of 
60 years. The yield assumed is as follows*: 



* Frothingham, E. H., White Pine Under Forest Management (Forest Service Bulle- 
tin No. 13, 1914, table 6, page 23). 



The Normal Forest 



63 



Table 8. Yield of White Pine in New Hampshire. 





Lumber yield 




Mean annual 


Current annual 




per acre, 




increment 


increment, 


Year 


board feet 




board feet 


board feet 


10 


0000 a 


x-N 








20 


4500 b 


n 


225 


«225 


30 


13900 c 


n 


463 plus 


940 


40 


32800 d 


^ 


820 


1890 


50 


49100 e 


JQ 


982 


1630 


60 


60200 f 


J^ 


1003 plus 


mo 


(70) 


(69900) 






970 



Adopting the formula we have, 

10(4,500+ 1 3,900 4-32,800-!- 49,100+—'—) board feet = 10(130,400) = 1,304,000 board 

2 

feet on 60 acres or 21,733 plus per acre. When a rotation of 60 years is assumed, the 

normal growing stock formula result may be figured for an acreage equal to the number 

of years in the rotation. 




Appendix F. Graphic Comparison of Normal Growing Stock Formula (for text, see 

Appendix F). 



64 Aiiicrica)i Forest Reinitiation 

70. Comparison of Normal Growing Stock Formulae.* In the followinj? table the 
normal growing stock has been calculated by the following formulae: column 2, the 
accurate yield table method; column 3, mean annual increment often inaccurate for 
board foot units; column 4, mean annual increment, where (after Moore) rotation is 
taken as total age minus age when tree is merchantable (in this case tree becomes 
merchantable at^i5 years); column 5, same as 4 but using the Wolff corrected formula 
(§66-67) which should be used instead of 4; it gives higher figures than the Moore 
formula but is more conservative than 3. 

Table 9. Normal growing stock in board feet per acre for rotations of 20 to 60 years 
by different formulae (figures evened off). 



I 
Rotation 

years 


2 3 

Yield table Mean annual 
method increment 

(Board feet per acre of 


4 
Mean annual 
increment (using r') 
forest) 


5 

Wolff 

formula 


20 
30 
40 
50 
60 . 


1,125 

3,816 plus 

8,700 
15,150 
21,733 plus 


2,250 

6,950 

16,400 

24,550 

30.090 


562 

3.475 

10,200 

17,185 

22,567 


984 

5,209 

14,094 

22,340 

28,209 



From the foregoing it is apparent that the normal growing stock in board feet when 
calculated on the basis of r' (after Moore) is closer to that given by the yield table 
method than the result if figured by the usual r X i formula or by the Wolff modifica- 
tion of Moore's r'. This is discussed at length in Appendix F. 

The use of another formula** is advocated for normal growing stock in selection 

forests, which Munger claims is simpler and perhaps sounder than the formula ^ •^ ' 

2 
just (m. a. increment = i) described. It is based on the theory that the base ae X y 
(figure 3) represents the length of the cutting cycle and the rectangles a', a", and a'", 
the amount left per acre after a heavy "selection" cutting. Munger uses current 
increment. The formula is as follows: 

Gn = *" + Reserved timber per cutting area X number of areas. The fol- 
2 

lowing arguments are given in favor of this formula: 

(i) It can be applied equally well to cubic feet or board feet. 

(2) It obviates the use of the length of the rotation "a very uncertain and meaning- 
less quantity in a forest cut by the selection system." 

(3) It does away with the necessity of deciding wdien a tree is to be estimated as 
merchantable timber which is so vital to tli£ Moore or Wolff formulae. 

71. Illustrations of Munger Formula. Suppose** that a virgin stand of western 
yellow pine averaged 16,000 board feet per acre and that three-fourths of it is cut by 
so-called "selection" cutting (thus leaving a residue of 4,000 per acre) and that the 
current annual increment on this 4,000 feet is 100 feet. Let us assume a cutting cycle 
of 50 years and a rotation of 200 years. Then, 

"At the end of a cutting cycle each coupe (cutting area), when ready for cutting, will 
contain its original 4.000 board feet plus the 50 years of increment (50 X 100 = 5,000), 
or a total of 9.000 feet." 

Taking I as equal to the "annual increment of whole forest (annual increment of 
each coupe X rotation)," then applying the formula we have, 



*A similar comparison is given in Schlich's Manual of Forestr}% Vol. Ill, 1900, p. 
225, but in cubic feet not reduced to a per acre basis. 

** Munger, T. T., A Formula for Normal Growing Stock in Selection System F"orests 
(P. S. A. F., Vol. X, 1915, pp. 18-21. 



The Normal Forest 



65 



Gn = 5.00 X 50 . _|_ (4,000 X 50) = 325,000 board feet on 50 acres or 325.0O0 _ ^^^^^ 
2 50 

i X r 
per acre. With i := 100 feet the result would be (with the formula - ) using of 
^ 2 

necessity current increment for i, •^ =: 10,000 per acre. For a more critical and 

2 

detailed discussion of this formula, see Part II, Chapter X. 

72. Flury's Normal Stock Formula with Illustration. Flury* suggests a reducing 

r X i 
factor c (Constant) to read Gn = c X r X i instead of the usual Gn = — — ■. This idea 

2 
is simply to substitute a constant reducing factor for each decade instead of using 

r V i 

Gn = ^^ for all ages. 
2 

Recknagel has worked out an excellent illustration** which shows what degree of 

accuracy can be obtained. But if great accuracy is required, why not use the yield table 

method to start with, since the calculation takes but a few minutes. Where no yield 

table was available, the value of c could not be figured; hence the method is not of 

practical value. 

73. A Normal Stock Calculation in Lodgepole Pine. A method of calculating normal 
and real growing stock in a lodgepole pine forest is illustrated by the table*** which 
follows: 

T.vBLE 10. Real and Normal Growing Stock and Periodic Annual Increment on the 
Bernice Division, Deerlodge National Forest, Mont. 



Age 
(I) 



Area 
(2) 



Normality 
(3) 



Growing stock 



Real 
(4) 



Normal 
(5) 



Periodic annual 
increment 



Real 
(6) 



Normal 
(7) 



Yield at 
the age 
of 140 

years* 

(8) 



Acres 

10 years i,570 

20 years 9,742 

30 years 5,511 

40 years 7,559 

50 years 1,412 

60 years 4,887 

70 years 1,928 

80 years 2,448 

90 years 2,092 

100 years 3,040 

no years 396 

Over 120 (average 
age 130 years) : 
Merchantable . 17,761 
Suppressed .. 4,145 
Total 62,491 



0.67 
.69 
73 
66 
67 
49 
40 
30 
20 
20 
20 



•35 
.10 



7,000 
CM. ft. 

95 
1,815 
2:293 
5,687 
1,731 
5,747 
2,267 
2,468 
1,582 
2,481 
342 



28,671 

1,890 

57,069 



7,000 

Cllr. ft. 

402 

1,205 

2,544 
5,089 
8,168 
10,713 
13,123 
14,998 
16,872 
18,211 
19,283 



61,062 
171,670 



7,000 

CM. ft. 

9 

121 

121 

284 

65 

136 

42 

31 

18 

18 



57 
904 



7,000 

CM. ft. 

40 

80 

134 

254 

308 

254 
241 

187 
187 
134 
107 



147 
2,073 



7,000 

bd. ft. 

16,662 

106,476 

63.448 

78,920 

15,058 

38,000 

12,215 

11,633 

6,628 

9,631 

1,254 



^ Normal yield, 15.840 board feet at 140 years on sites of average quality; 78.7 per cent 
of area overstocked; 20.5 per cent of area understocked; 0.8 per cent of area normally 
stocked. 



* For a more complete discussion, see review by Fernow (Forestry Quarterly, Vol. 
XIII. 1915, pp. 108-113). 

** Recknagel. A. B.. Forest Working Plans, New York, 1917, p. n. 

*** Mason, D. T., Utilization and Management of Lodgepole Pine in the Rocky Moun- 
tains (Forest Service Bulletin 234, 1915, pp. 36-39). The columns have been numbered 
to facilitate reference in this text. 



66 ' American Forest Rei^^ulatlon 

Tlie figures for real growing stock (4), the present total stand were obtained by 
multiplying the normal stand (normal according to an empirical yield table) per acre 
for each age class (as given in table 9, Forest Service Bulletin 154) by the "normality" 
(3) or per cent of stocking, a figure which was multiplied by the actual area occupied 
by each age class. In the case cited in the preceding table the forest comprised 62,491 
acres of productive timber land, the rotation was 140 years (divided into 14 periods of 

10 years each) so the normal area per age class was — 4y__ 3=4,463.6 acres. 

14 
The normal growing stock for the lo-year age class was then found by multiplying 
the normal yield (from table 9, Forest Service Bulletin 154) by this normal area. This 
figures 90 cu. ft. X 4,463.6 = 94,671, or 95,000 cu. ft. This simple method of comparison 
is of value under the extensive conditions prevailing in the West. 

74. Importance of Normal Growing Stock in the United States. The 

reason why tlie computation of normal growing stock is important — even in 
extensive American forest management — is because of its usefulness in yield 
regulation by volume formula methods, which may often be sufficiently 
accurate for early regulation. 

This normal forest, which we have been discussing, in theory might be 
attained on an area of definite size and for a rotation of given length after 
the lapse of a complete rotation, if all other considerations were sacrificed 
to the attainment of a proper series of age classes, and provided that all 
accidents or injury to the forest could be completely excluded from our cal- 
culations throughout the entire rotation, and provided further that no change 
in the existing rotation need be made because of different economic condi- 
tions. Because of the impossibility of attaining normal age classes, even if 
these sacrifices were made, the proper policy is to build up as good an age 
class series as possible by working groups and let the distribution on the 
total forest area take care of itself. The gradual attainment of normal age 
class distribution involves cutting stands before or after the rotation age. 
This is not so commercially undesirable unless carried to such extremes that 
serious volume loss results. Such sacrifices are usually warranted to a certain 
extent in regulatiori, although it must be recognized that a later change in 
the length of the rotation requires a rearrangement. 

75, Quiz. Distinguish between normal forest and normal yield table. 
What must a forest possess to be normal? 

How are forests usually abnormal? 

Discuss normal age classes: how is the distribution affected by artificial and natural 

factors? 

Discuss normal increment. 

Discuss normal growing stock. 

r X i 
Explain the growing stock formulae Gn = ^ ; why is it faulty? 

2 

Should growing stock be calculated in spring, summer, or autumn? 

]- \/ J r' V i ' Tr' s'^ 

Which is the better formula for board feet "^ or '^^ or "^ -^ ? 

22 2r 

Explain the formula * ■^ ^^ plus Res. per cutting area X number of acres. 
2 

Why is it useful? Its drawbacks (see chapter X)? 



The Normal Forest 67 

Explain the calculation of growing. stock by the yield table method. 

Why is this most accurate? 

Why is the yield multiplied by 10 in the formula? 

Why is J used? 

Why in a 60-year rotation is a normal forest of 60 acres assumed? 

What is P'lury's constant? 

How is it computed? 

What is its advantage over the yield method? 

Why are normal growing stock calculations important even in extensive forestry? 



CHAPTER \II 
REGULATING THE CUT 

76. Definition and Aims of Regulating the Cut. Regulation of the cut in 
the narrower sense means the fixation in advance of the annual or periodic cut, 
2vhich in the normal forest would be equivalent to the annual growth"^ (G., etats- 
bestimmung, ertragsbestimmung; F., fixation de la possibilite). 

The broader aim of regulating the cut is three fold : 

(i) To cut each stand at rotation age (maturity) and secure the maximum 
required product. This is largely economic. 

(2) To cut about the same amount of material of the most valuable 
product each year or decade. This is economic and financial and is all 
important. 

(3) To reproduce about the same area each year or decade. This supple- 
ments paragraph i. 

(i) If each stand is cut at maturity, it will probably benefit the stand at 
the expense of the future of the forest because no progress w^ould be made 
towards a regular yield which ultimately looks for regular age class distri- 
bution. On the other hand, if stands are cut when very overmature or imma- 
ture, costly silvicultural sacrifices may result. 

(2) If the present volume output is considered of first importance, it will 
mean a sacrifice in future orderliness for present immediate regularity of cut. 
For a forest that has been impoverished proper regulation demands that its 
stock be gradually built up ; while a forest with excess stock should have 
this excess gradually reduced. This may decrease or increase the present cut 
but need not seriously interfere with its regularity. 

' (3) Unless a reasonably uniform area is reproduced each year or decade 
the ultimate normal distribution of age classes (and hence of the cut) will 
be defeated. To reproduce equal areas each year or decade is the least impor- 
tant immediate object but the most important ultimate one. 

77. Basic Policy in Regulating the Cut. The first step in regulation is 
naturally to take stock and to divide the forest into timber productive and 
non-productive types as well as into management subdivisions. The next 
step is to obtain accurate growth data on the productive areas. 

Before fixing the annual cut — one of the aims of regulation — the following 
general principles should also be recognized as basic : 

(i) The forest should be managed so as to furnish the maximum quantity 
of the kind of material required by the owner. Where desired, scenic and 
protection working groups may be excepted from regular commercial man- 
agement. 



*ln the normal forest the current growtli is the same as the mean annual growtli. 
Before commencing chapter VII the student should read "Studies in French Forestry." 
pages 243-260, so as to have the modern working plan clearly in mind. 



Regulating the Cut 69 

(2) Other things being equal, cutting should be directed to the over- 
mature and mature stands and age classes. 

(3) Forest management must first provide for the prolongation and per- 
petuation of the timber supply — sustained forest production — needed by indus- 
tries and for the stabilization of labor, if this can be done without too heavy 
a sacrifice of technical aims. 

(4) The technical aims of every working plan lead to (3) above and 
should be : proper distribution of age or diameter classes, normal growing 
stock, and a proper silvicultural condition ensuring suitable regeneration and 
a perpetuation of the forest as a whole. Under certain conditions fire or 
watershed protection may be the chief technical aim. 

These aims must be carefully weighed and correlated.* But it must be 
recognized that no regulation or organization of a forest has the slightest 
chance of success unless it is based upon sound basic silviculture, because 
forest regeneration and forest production — both dependent on sound silvi- 
culture — must be successful or there will be no real forestry. 

In our extensive western forests, which must at present often be logged by 
corporations capable of maintaining and operating large capacity plants with 
railroad feeders, there is usually presented the following problem which is 
exceedingly difficult to compromise without serious sacrifices : 

(a) Devastate mature and over-mature timber rapidly to avoid loss from 
decadence with a consequent heavy cut during the first cutting cycle, a 
cut which cannot be maintained after the store of ripe timber is harvested. 
The proper age class distribution will be delayed for a considerable period. 
This is not forestry. 

(b) Cut off mature and over-mature timber gradually assuming a consid- 
erable and increasing loss from decadence but aiming at a yield during the 
second cutting cycle equal or nearly equal to the original cut. The age class 
distribution will be secured at an earlier date than if (a) is adopted as the 
fundamental cutting policy. The actual losses from decadence are often over- 
emphasized. 

(c) Compromise between (a) and (b) so as to avoid part of the loss from 
decadence necessitated by (b) but obviating the serious hiatus of cut required 
by (a). 

This problem must be decided in each case before the details of regulation 
can be intelligently worked out. Nor must the silvicultural requirements for 
proper regeneration be lost sight of. With plan (b) certainly regeneration 
will be surer than with (a) in difficult soil conditions such as often occur in 
Arizona. The administrator should always remember that stability of pro- 
duction is more important than to save timber that jnay be lost. 

Speaking in terms of intensive selection forests in France, Biolley** argues 
that since the cut depends on the amount of the forest crop, it is better to 



* Eldredge. I. F., says (J. of P.. 1920, pp. 284-291) the aims of management plans in 
the national forests of the Southern States are: maximum production of merchantable 
timber, permanence of local industries and forest labor, salvage of deteriorating timber, 
restocking mistreated areas, regulation of cut (by stand method). 

** Biolley, already cited, p. 56-57. 



70 A)ncrican forest Regulation 

decide on the cut after it is seen what the aniomit of the crop really is. He 
says : 

"The growth, which is the fruit of the treatment, can only be known after the product 
is disclosed; the yield can thus only be a prediction of the harvest (more or less 
strongly justified) for a very short lapse of time .... It is useless and an error to 
make predictions for a long time ahead; it is even worse to fix a yield for a rotation 
as is done, even if it is subject to revision every twenty years, for the yield-decree ties 
the hands of the forester, and substitutes for the worry of the silvicultural aim of the 
cutting, preoccupation over the volume which it is forbidden to exceed or obligatory 
to reach; moreover, tlw trcatincnl (the essential thing) gives way to regulation and 
cannot be the o])jective." 

What Biolley wants is not an unposed yield l)Ut a crop proposal. He desires 
to emphasize the need for placing more stress on silviculture and less on 
the regulation mathematics — a policy essentially sound if not carried to 
extremes. There must always be leeway in applying a prescribed yield 
figure — silviculture must not be throttled — but this is no excuse for not 
prescribing, systematizing and regulating the cut. 

78. To Attain Regulation Compromises are Necessary. There is thus a 
conflict between the objects of regulation which entail a compromise. The 
complete attainment of a single goal (such as a sustained annual or periodic 
cut) may be sacrificed so as to attain partial progress toward age class 
distribution, or cutting stands when they are ripe. In another case it may be 
wise to cut before or after maturity so as to have a more regular immediate 
annual cut for a local sawmill or to insure better age class distribution during 
the next rotation. In still another instance more or less than the increment 
may be cut to attain normal stocking or to allow the development of young 
stands or prevent the decay of over-mature timber. A point in theory to 
remember is that under no circttmstances would the annual cut be exactly 
equal to the mean annual increment unless the normal forest had been 
attained — difficult to attain even under intensive European conditions.. 

79. Relation Between Increment and Growing Stock, The principle deter- 
mining the relation between increment and growing stock is normally as 
follows : one-half the increment will be upon trees cut within the rotation and 
one-half on the nczv crop not yet started. At the end of the rotation all 
timber nozv standing, including seedlings, will haAC been cut and the growing- 
stock will consist of entirely new stands. 

For accurate regulation accurate estimates are needed. But these cannot 
precede the demand, and seldom can be complete for entire forests because 
only areas where sales are a possibility can be estimated accurately and 
intensively. On the other hand, no real regulation is possible till the working 
group has been fully covered by some form of estimate. It is for this reason 
that rapid, cheap and approximate timber surveys are fully justified on areas 
not accessible for sales for many years to come. But the resulting regulation 
cannot pretend to be very accurate in detail, nor is this accuracy necessary 
as long as the cut is fairly conservative. In fact it would be faulty forest 
management to pay for intensive timber surveys when it was a certainty that 
the stand could not be cut over for many years. Until there is a market 



Rci::;itlafiiif::; the Cut _ 71 

with transportation to it regulation must be preliminary in character. Thus 
there is always a creative period when approximate methods are sufficiently 
accurate f(ir obtaining increment and growing stock. Yet Moore* is exactly 
correct when he says: 

"A thorough understanding of the silvicultural requirements of the different trees and 
of the methods of cutting which will result in a maximum production of the most valu- 
able ones is the first essential. In the long run it is generally far better to have over- 
cutting under proper silvicultural methods than to have a perfect regulation of the cut 
with poor methods of silviculture." 

If one must choose between two evils, sound silviculture must not be slighted; 
but this does not justify devastation. 

80. Definitions and Classification of Methods of Regulating the Cut. Gen- 
eral classification of methods of regulating the cut may be recognized: 

( i) Normal stock or formula methods, zvhen the amount of cut is determined 
by comparison of actual Tvith normal conditions and the cut is in part regulated 
by a volume formula for a rotation or equalization period. 

1 2) .lllotmcnt methods, when a rotation is fixed and for a given year or period 
of the rotation a certain area, a certain amount of stock, a certain number or sise 
of trees is allotted to be cut. 

I ^) Individual or stand methods, when each stand is investigated for its 
maturity and designated for cutting, provided other age classes are in existence 
to assure continuity of crops. (This is usually supplemented by area and 
volume check.) 

An attempt has been made to merge the allotment principle (namely of 
alloting stands for cutting in a definite period) with the various methods 
which make use of the alloting of stands directly or indirectly. 

A glance at table 11 shows the classification of regulation methods adopted 
in this volume as contrasted with Recknagel, Roth, and Schlich. The writer 
has tried to select one typical form method for each different class of regulation. 
Volume methods have been given first because they have first been used in 
the United States with irregular \-irgin stands. In this volume the methods 
have been arranged as follows: 

A. Volume basis. (1) Growing stock, (2) Increment, (3) Increment and 
growing stock, (4) Size classes, and (5) Tree as unit. 

B. Area basis, (i) Pure area, (2) Area (and age) allotment by periods. 

C. Area-volume (and age) basis, (i) Volume and area — volume allot- 
ment by periods, (2) Americanized stand selection, and (3) Cutting cycle 
and felling reserve. 



* Moore, B., Methods for Regulating the Cut on National Forests (P. S. A. F. Vol. 
VII, 1912, p. 11). 



72 



American Forest Remulatioi 



Table i i . 



Relative Classification of Methods for Regulating the Cut used by Different 

Writers. 



Schlich (p. 311 1, vol 
3d Ed.). 

T. Stand 



III, 



Roth (p. 139-159 also p. 
VII). 



Recknagel (p. VIII, also 
p. 67-126). 



Woolsey in this volume. 



Selection 

(Judeich). 
I'ixed Annual 
Coupes. 

Allotment b>' 
Periods 

1. Area. 

2. Volume. 

3. Area and Vol- 
ume. 

Increment and 
Growing Stock. 

1. Austrian. 

2. Hundoshagcn. 

3. Von Mantel. 

4. Brandis. 
Increment and 
Growing Stock 
Combined with 
Al 1 o t m e n t of 
Areas to Periods 
(Heyer). 



A. Area methods. 

1. Fixed yearly cut. 

2. Area allotment. 

3. Limited area allot- 
ment (Judeich). 

B. Volume Methods. 

1. Volume allotment. 

2. Growing stock. 

a. Austrian (and 
Heyer). 

b. Hundeshagen 
(and Von 
Mantel modifi- 
cation ) . 

c. Combined 
methods (see p. 

158). 

d. Diameter limit. 



A. Volume Basis. 

1. Growing Stock. 

2. Increment. 

3. Increment and 
Growing Stock. 

4. Size Classes (and 
Periods). 

5. Tree as Unit (and 
Increase in Size). 

B. Area Basis. 
I. Pure Area. 



A. Area. 

B. Volume. 
II. A. I'ixed .\nnual 2. Area allotment. I. CJrowing Stock 

Basis. 
B. Allotment by ment (Judeich). i. Von Mantel. 

2. Masson. 
II. Increment. 

I. Current Annual 
Increment. 
III. Growing Stock 
and Increment. 

1. Austrian. 

2. Karl. 

3. Hundeshagen. 

4. Brcymann. 

5. Heyer. 
D. increment and I.s8). IV. Diameter Classes. 

1. French method 
of 1883. 

2. Indian method. 

3. Diameter class 
method (Huf- 
nagle). „ 

C. By Area and Volume. ^ 
I. For Entire Forest. ^ 

I. Gurnaud. ^ C. 

II. Based on AgeP-i 
Classes. >+- ' 

1. Direct method. ^ 

2. Hufnagl. g' 

3. Stand Method^ 
(Judeich). ^ 

III. Periods. ^j 

1. Area. '7. _ 

2. Volume. (^ 

3. Area ^nd vol- 
ume. 

4. American "~ 
method (Chap- 
man ) . 

The following methods of regulating the cut cited by Recknagel (his 
symbols have been used) have not been described in this volume for the 
reasons given : 

Table 12. List of Formulae Omitted from Text. 

Page* Scheme or Basis. 



2. Area Allot- 
ment by Periods. 
Area-v o 1 u m e 
Basis. 

1. Volume and 
Area - volume 
Allotment by 
Periods. 

2. Americanized 
Stand Selec- 
tion. 

3. Cutting Cycles 
and Felling 
Reserve. 



Name of method 



Masson's method 



Swiss method** 



Austrian formula 
"Kameraltaxe" 



Hundeshagen's 



Why discarded. 



74 Same basis as Von Mantel. Duplication. 



Divide volume of oldest size Faulty regulation unless forest 
74 classes by c. a. i. of entire normal. Scientific interest 
stand to get number of years only, 
volume of class must last. 



78 



- ; I ga 



gn 



Cut = i + 

r 

where i = actual m. a. i. 



Because r is rigid; it is better 
to distribute surplus or defi- 
cit according to local condi- 
tions. 



y „y ,Ty IdcttUcal to V ou Mantel or 

Cut=:- = - , or y = v - Karls "Austrian," if period 

^' "^ "^' of distribution = J^ rotation. 



8.=5 



Regulating the Cut 



73 



Breymann's 



Heyer 



86 



y = ny (here a=:age). 
na 



Because surplus or deficit dis- 
tributed over whole rotation. 



n + IX — nv 

X 

where i := a. m. a. i. 
X =: X years or period of dis- 
tribution. 



See paragraph 85. 



Diameter class method 
(Hufnagl) 



Cut = vol. of trees or of di- 

r 
ameter classes ^ years + A rigid scheme rather than a 

over-plus increment thereof distinct method of regula- 
tion. If volume of upper 
in years ; tliis sum divided classes very deficient, there 
4 might be no cutting. 



by 7 equals the cut. 



(Average volume per acre = Too rigid and no basic method 



Direct method 
(Hufnagl) 



108 



volume of oldest stands di- 
vided by area occupied by 
stand) X allowed area to be 
cut := volume to be cut. 



of regulation. If data it re- 
quires is available, modified 
allotment method feasible 
and preferable. 



Hufnagl's method 



Yield = rotation 

volume-)-areaXincrement*** X 

rot ation 
2 



See above. 



* In Recknagel's "Theory and Practice of Working Plans." 

** C. H. Guise, in J. of F., 1917, pp. 564-573 on "The Swiss Method of Regulating 
the Cut in Practice" advocates a further trial of the method and states it gives a higher 
cut than does the Von Mantel formula in the case cited. 

*** Mean annual increment gives a cut 10-20% less than if current increment used. 



CHAPTRR VIII 
(A) VOLUME METHODS OF REGULATION 

8i. General Principles and Classification of Volume Methods/-' Formula 
methods should rarely be relied upon as the sole basis for establishing the 
cut ; they should be used as a rough check against other methods that take 
into consideration Nolunie and area as well as age. The use of a formula 
may be necessary in order to answer a problem in yield which does not yet 
justify the use of more intensive methods. Under American conditions 
the use of the board foot unit of measure is a dangerous complication 
in the use of \olume because young stands may yield no board feet and yet 
the aggregate of trees have a consideral)le cubic content per acre. The trees 
from such stands yield cordwood but no lumber. Therefore the use of an 
area check when using formulae methods is all the more essential. 

Care has been taken to recommend certain formulae methods for use under 
specified conditions as differentiated from methods of mere scientific interest 
which nevertheless are explained for the information of the student. 

Regulation on the basis of volume has been classified as follows: 

Main Basis 

(A) Volume. (i) Growing stock. (a) Von Mantel. 

Gurnaud. 

Austrian. (Other 
forms of Austrian 
formulae discard- 
ed.) 

F"rench method of 
1883. 

Indian single tree 
method. 
Diameter hmit. 

Iiitenitcdiafc yield. Whatever mctliod of calculating the cut is employed, 
the regulation i)f the intermediate cut from thinnings, clearings, weedings. etc. 
should be leased upon the principle of cutting approximately equal areas 
annually or periodically, it is most essential to keep the young stands from 
becoming too dense and to eliminate undesirable trees as well as the less 
promising species ; then if intermediate cuttings be limited by volume, it 
might occur that areas in need of thinnings could not be reached. Such areas 
must be cut over systematically and tliis can be best insured by co\-ering a 
certain area eacli vcar even if the volume cut is slightly exceeded. This 



Secondary Basis F 


orm 


(i) Growing stock. 

(2) Increment. 

(3) Increment and 
growing stock. 


(a) 
(a) 
(a) 


(4) Size classes (and 
periods). 

(5) Tree as unit. 


(a) 
(a) 




(b) 



* Methods noted as "of scientific interest" nii.nlit have l)een termed "of academic 
interest." 



Volume Methods 75 

vield from intermediate cuttings is usually estimated so as to secure a tenta- 
tive volume figure for the annual or periodic budget. 

In the treatment of the various formulae the method has been (i) defined, 

(2) discussed and the advantages and disadvantages summarized, and then 

(3) illustrated by practical examples. Methods noted as "of scientific inter- 
est" will not generally be used in the United States. 

82. (i) Volume Regulation Based on Growing Stock, a. Von Mantel's* 
method (chiefly of historical interest but often recommended during the 
initial stage of organization) is as follows: 

actual growing stock . , ^ Ga 

Annual cut = ^^Totation ' ^•^- """^''^^ '"' = >^ 

where r' is used, this becomes : annual cut ^ - 



/2 r- 



Tj • .u n rXi ^ r'X 1 

Basis : on theory Gn ^ or Gn = 

■'2 2 



surplus distrilnited over — years." It gives the same results as Hundes- 

r X i 
hagens when he finds Gn by the method. 

As Moore** points out. if r' is used "the yield will be the same as that 
given in the Austrian formula in which Gn is found by the use of r' and the 

surplus distributed over - years." But the Wolff formula is preferable to 
Moore's although the basic ideas are similar (see §66-67). 

Discussion. Since this method does not require a study of increment, it 
has been widely used by the Forest Service in its rough preliminary regula- 
tion. The volume to be cut is the keynote instead of the area reproduced 
or the age of the stand. 

This formula is faulty in that it assumes normality but is always applied to 
the actual forest which cannot fail to be abnormal. By this assumption it 
provides that an amount equal to the present growing stock, surplus or 
deficit included be cut in half the rotation. The condition of the forest after 
that time will depend on the amount of increment laid on, 

a. On stands previous to cutting 

b. On stands originating after cutting 

c. On young stands becoming of estimable size after the calculations are 
made. 

Howard*** suggests a modification of Von Mantel's formula to— ^ for use 



* Masson's (France) formula is identical only it is written " - instead of — ^. 

r ^r 

** Ibid. It should be remembered that about twice the normal growing stock is pro- 
duced by a forest during the rotation; therefore the amount that can be cut is 2 Gn. 

***J. of F.. Vol. 46. pp. 417-421, August I. 1920. Von Mantel's formula, or modifica- 
tions of it, should primarily be used as a check against other methods as has been ex- 
plained in the text. The disadvantages in using this formula, or any other formula, may 
be diminished if there are very frequent recalculations of yield based on a re-estimate of 
the growing stock. The main difficulty is that frequent estimates, even under intensive 
conditions in Europe, are a burden of expense. 



76 



American Forest Regulation 



in Indian selection forests. This has the same disadvantages as Von Mantel's 
but might be a useful idea under certain conditions. 

It follows that over-stocked forests of over-mature timber will be stripped 



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2o 30 Ao ^o <oO 10 %o qo 100 no 

C^IT >OvC CORDING TO VoM M-A^^J-rE-U (\iM Coi5.r7,C-OTE nj 



Fig. 5. Illustration of the Result of Using a Correction Factor for \'on Mantel's 

Formula. 



of all merchantable liml)cr in half the rotation ; this- would probably save 
waste but might be a serious overcut where the cut was in board feet ; the 
remaining stand might be too small for merchantable sawlogs. Frequent 
re-estimating and re-calculation of the cut would lessen these dangers. 

The formula error of exaggerating the cut for an impoverished forest and 
cuttins: too little on one that is rich in material can be modified bv correction 



Volume Methods 



77 



factors. The per cent of the growing stock to be cut, Schaeffer says,* should 
be higher with 60 cords per acre than with but 20. 

"To enable an impoverished forest to restock less than the amount indi- 
cated by the formula should be cut; the per cent cut should be reduced." 

This correction factor is systematized by considering that the per cent 

given by the formula (cut = - ) is approximately correct for an empirically 

2 
normal stand. Then a table is constructed diminishing the formula per cent 
0.1 for stands that are 50 cubic metres less than normal and increasing the 
per cent o.i for each 50 cubic metres above normal. A correction factor was 
then worked out for 5 soil qualities corresponding to rotations of 120, 140, 
160. 180, and 200 years for silver fir. The idea can be applied in the United 
States, where this formula is used. For a second quality silver fir stand 
(with a rotation of 140 years) the actual volume to cut by the formula (cor- 
rected and uncorrected) is illustrated by figure 5. 

Where r' (after Wolff) is us.ed instead of r, this means that the merchant- 
able timber will be cut even more rapidly. 

Disadvantages: 

(i) It is inelastic because the surplus or deficit is always taken up in 
half the rotation ; if the cut can be frequently re-calculated upon the basis 
of new estimates this objection is less serious. 

(2) With board feet it gives too low** a cut unless r' is used. 

(3) It rests on faulty regulation because it neglects the age and rate of 
growth of stands and area of cuttings (an area check corrects this to a certain 
extent). 

(4) Only of use in preliminary and crude regulation (even then should 
be used only with area check). 

(5) It has not been thoroughly tried out by experience*** (abandoned in 
Europe). 

Advantages: 

(i) " Will gradually lead to the establishment* of the normal 

growing stock" and " adapts the cut to the actual growing stock on 

the land " 

(2) It is easy to apply since it merely requires the actual growing stock 
and rotation ; it is handy. 

(3) Of value in preliminary and crude regulation where an approximate 
volume check is required by law (as on National forests). 

Illustration. Given:- Case (i) Ga= 1,043,000 board feet. 

Case (2) Ga^ 1,304,000 board feet. (This coincides with Gn.) 
Case (3) Ga^ 1,565,000 board feet. 



* Schaeflfer, A., Un Correctif a la Methode Masson, Bulletin de la Societe forestierre 
de Franche — Comte at Belfort, No. 3, 1905. 

** Ibid., p. 18. 

*** Roth, Filibert, Forest Regulation, p. 157. 

* Schlich, Vol. in, p. 320. 



yS American Forest Regulation 

Where r =60, r' = 45 years and the area 60 acres. 

Then by cut = ^/ Case (i) i£43:22^ ^34,766. 
ViV 30 

Case (2) ''3O4.0O0 =43,466. 
30 

Case (3) I:565-000 =52,166. 
30 

Reference is made to a comparison with the Austrian formula §85; see also §66-67. 

83. (2) Volume Regulation Based on Increment Alone. Since all forests are 
abnormal (see Chapter VI), the use of increment alone for purposes of regulation is 
considered dangerous and inadvisable especially under American conditions. 

The idea expressed in the Gurnaud* plan is little more than of scientific interest. 
Gurnaud simply treated the forest as a sample plot and increased or decreased his cut 
according to the results of past cutting modified by the dictates of current silviculture 
and market conditions. If the forest v^'as about normal (on an empirical basis), the 
annual cut was supposed to equal, 

(Present Ga — former Ga) + (cut between stock takings) 
(Years between measurements) 

In applying the allowed yield they endeavored to cut according to the empirical 
representation of age classes in the ideal selection stand for the species in question. 

This is of course faulty in that it presumes (unless applied with great judgment) the 
growth should be the cut — a mistaken ideal. It also necessitates frequent remeasure- 
ment, a factor which is exceedingly costly in the United States. 

Furthermore the Gurnaud* idea really goes further and seems to subordinate the 
modern conceptions of a fixed rotation, of a sustained or fixed yield, or of a normal 
forest to a flexible method of silviculture that will give the owner the greatest possible 
grozvth. The forest is to be intensively managed as a number of sample plots with 
frequent stock taking (every 5 or 10 years). The cut is to be based on the results 
obtained over short periods rather than on predictions for several decades. The sus- 
tained yield and the ideal normal forest will be secured. Biolley claims, by carrying out 
the aim of getting the largest possible growth with the minimum possible growing 
stock. The method aims at largely subordinating forest regulation to silviculture. As 
a method it would rarely be applicable in the United States even under intensive con- 
ditions; moreover, the method is really an idea or policy rather than a recognised and dis- 
tinct system of regulation. It is an idea that could be applied with any regulation method 
and as a matter of fact, is made use of by the best management men in France, when 
applying the French method of 1883. In fixing the yield the regulator studies the area, 
volume, age classes, and growth on each lot. 

Disadvantages: (1) If current increment is taken as the basis of the cut. it will be 
too small with decadent forests and too great with immature stands. 

(2) If mean increment is taken (if actual mean is taken for each age class, then it 
is much too high for young stands and too low for overmature stands) overmature 
stands will not be reduced, nor immature built up by merely cutting the increment 
because the present amount and age of timber is not considered. 

(3) It is expensive and difficult to measure the increment on the entire forest. 



* Those who wish to study Gurnaud's ideas on regulation shouk^refer to La Methode 
du Controle, P. Jacquin, Besancon, 1886, pp. 1-124; also La Methode du Controle a'l 
exposition universelle de 1889 published in 1890. See Recknagel (ibid.) p. 106 and pp. 
74-77; also Studies in French Forestry by T. S. Woolsey, Jr., John Wiley & Sons, 1920, 
pp. 206 to 243. 

** Recknagel. A. ?>.. Forest Working Flans, described (pp. 74-/7^ as the "Swiss" 
method regulation by incremeiit alone, but the writer prefers not to introduce this to 
American forest students. 

* Biolley already cited, p. 29 and 59. 



Vohiuic Alctlwds 79 

C4) To be at all satisfactory there must be a nornial age class distribution which is 
not found. 

Advantages: None; but often of interest and value as a rule of thumb check on actual 
increment under the practical conditipns that have prevailed in the forest. Losses 
tlirough suppression, etc. are shown in the calculation. 

84- (3) Volume Regulation Based on Growing Stock and Increment. 

The stumbling blocks to this class of formula are: (i) How to calculate the 
normal growing stock; (2) whether to use current or mean annual incre- 
ment; should this be the normal or actual increment?; (3) the term of years 
during which the surplus or deficit should be distributed.* 

The best results in regulation based on growing stock and increment are 
obtained by the following methods : 

(i) Calculate the normal growing stock by the yield table method (see 

r X i 
par. 68-69) ^vhere practicable; if not, use or where board feet are used, 

substitute ^ ^^ ~ ^ ^ (see § 66-67). 

(2) Use actual mean annual increment instead of the current annual. 
Normal increment should not be used. 

(3) The surplus or deficit should be distributed according to the condi- 
tion of the stand and according to the economic possibilities for saving. 
Rarely, if ever, will the entire rotation* be used as the time within which to 
distribute a surplus or deficit. 

The distinctions between the various formulae based on growing stock 
and increment are illustrated in the table which follows. 

Table 13. Distinctions Between Formulae Based on Growing Stock and Increment. 



Name of Historical 

Method Reference Formulae Remarks 

Austrian (as Roth, p. 150 Cut = actual M. Actual mean annual incre- 

modified by Schlich, p. 314 , ; 1 Ga — Gn ment is used and it is as- 

\'on Gutten- Recknagel, ' x sured x is flexible rather 

burg or p. 78 (Most practical adaptation). than the rotation time. 

Heyer). 

Roth (Of scientific interest.) Actual current annual is 

Schlich Cut = actual current An. i used. Not described by 

Karl's* (not given) , Ga — Gn Roth and Schlich. 

Recknagel, ' x 

P^3 

Hundeshagens** Roth, p. 56 (Of scientific interest.) Avoids the calculation of ac- 

(see Von Schlich, 317 Cut = Ga X — ^"^^ increment. Is inelas- 

Mantel, p. 75) Recknagel, Gn tic Basis incorrect. 
p. 85 



* Roth. Filibert. Forest Regulation, p. 151 holds, as does Von Guttenljerg. that it is 
an error to consider the Austrian formula as spreading the surplus or deficit over an 
entire rotation. See also Indian Forester, March 1922, pp. 122, 126. 

** Those who are interested in the variations between these formulae are referred to 
page gi of Forest Working Plans by A. B. Recknagel, but it should be borne in mind 
that the variations will change according to the period of distributing the surplus or 
deficit and according to the data assumed as a basis for the example. 



So American Forest Regulation 



Roth (Of scientific interest.) Normal age = half the rota- 

Schlich Cut = M. An. i X tion. Has the disadvan- 

Breymann's** (not given) Normal Age tage of being inelastic. 

Recknagel, Actual Age 
p. 86 



Roth, p. 154 r t — Ga + i — Gn i is the actual M. an. incre- 

Hevcr's** Sclilich, 325 ^^^ — ^ mcnt for rotation. 

(see par. 85). Recknagel, Roth does not distinguish See discussion of Austrian 

P-89 the Heyer formula from method where x is van- 

the Austrian. ^^le. 



Of these formulae Heyer's is the most accurate in theory, but since for- 
mula methods are approximate, a simpler form is preferred. 

To give satisfactory results the formula must be based on actual mean 
annual increment and the surplus never rigidly distributed over the wJwle 
rotation. An analysis of the formulae shows that Karl's can be discarded 
because it is based on actual current annual increment and possesses no 
advantages secured by the flexible type of the Austrian formula. Hundes- 
hagen's is too inflexible because there is no choice as to decreasing or length- 
ening the time for the distribution of surplus or deficit. Breymann's presents 
too intricate a problem when it comes to determining the actual average age. 
Heyer's embodies the same principles as the modified Austrian but no 
improvement. Therefore but one type of formula is described and illustrated. 

85. (a) The Modified Austrian Formula. (Von Guttenberg form; often 
termed Heyer modification). The formula reads: 

Annual cut = actual mean annual growth -f 

actual growing stock — normal growing stock 

-=- years over which cut is distributed 

i.e., annual cut = "^- ^- '- + Ga-Gn_ 

X 
Discussion. The increment used is ordinarily the actual mean annual incre- 
ment. The actual growing stock must be obtained by an inventory of the 
forest. The normal growing stock is computed preferably from yield tables, 

or from the formulae L212 or ^ ^ (see § 67 to 68). The surplus or deficit is 
2 2 

distributed in a shorter or longer period according to the dictates of good silvi- 
culture and good business. If the timber were very over-mature, the tendency 
would be to reduce the surplus rapidly. If a deficit existed, it should not be 
made up so quickly that the resulting forest would contain diseased timber. 
Nor could economy be practiced to such a degree that the yield for local de- 
pendent industries would be dangerously reduced. Where the actual stock (as 
in the West) consists largely of mature and overmature timber, the apparent 
surplus over the theoretical normal stock is not potentially as great as it might 
appear to be. For when all the over-ripe timber is cut for silvical reasons there 
is likely to be a deficit in growing stock because there is no middle-aged 
timber. 

The Austrian formula gives the same results as Von Mantel's (see § 82) 
if the period of distribution (or equalization) is taken at ^ r.' With longer 



Volume Methods 8i 

or shorter periods of distribution the cut by the Austrian formula will be 
less or greater than that by Von Mantel's.* 

Before using the Austrian formula it is well to bear in mind its peculiarities, 

(i) Application to a given volume in the forest. The smaller the mean 
annual increment on this volume, the more overmature the forest and the 
larger the annual cut because the normal stock depends on increment ; the 
increased cut due to the surplus more than offsets the loss due to the small 
increment. The result of cutting is a large reduction in the surplus. Hence 
if actual current increment in old stands were used, heavy cutting is indicated 
which is obviously good forestry. Conversely, the larger the increment, the 
smaller the cut, until the forest becomes normal, because a large normal 
stock is indicated. 

(2) With a long rotation the cut is diminished because of the increase in 
the normal stock. Therefore a conservative cutting of the present forest is 
best secured by adapting as long a rotation as possible. 

With a longer period for the distribution of the surplus the cut is of course 
diminished ; again, if there is a surplus in the growing stock, then the cut 
would be increased by a short period of distribution. 

A conservative cut demands the use of the actual mean annual increment 
at its culmination as the basis for the normal stock. For a rapid cut use 
actual current increment (especially in old stands), with a short rotation and 
a short period for distributing the surplus. 

Disadvantages: 

(i) It is highly artificial and tricky, especially with a board foot measure, 

unless the normal stock is calculated by the formula (see § 66-67) 

or from yield tables; even then it is subject to error. 

(2) It assumes that i and Gn remain constant whereas they are contin- 
ually changing because of natural and artificial causes. This is not as serious 
an objection as might appear because it is corrected at the time of revision. 

(3) It ignores area and age. It is an "office" rather than a "field" method 
of regulation. 

Advantages: 

(i) It is elastic because there is wide choice as to the number of years 
in which to distribute the surplus or deficit. 

(2) The objective of always trying to approach the normal stock is clearly 
before the regulator. 

(3) Adapted to extensive forestry and clearly distinguishes between cap- 
ital and income, but its value lies chiefly in its use as a check on other 
methods. 



* For example given i=ioo, r=ioo, Ga = 7,000, Gn = ^— ^^-^° = S,ooo and if 

2 

x = 5o years, the Austrian formula works out 50 X 100+ -' = 140. while by Von 

50 

Mantel we have ~'^^ = MO, an identical figure. The Austrian and Von Mantel give 



r X 1 
the same results only in case the inaccurate — formula is used to calculate the normal 

2 
growing stock. 



82 American Forest Regulation 



'ustrations. 


G; 


iven 


for 


a forest o 
Case (i) 


>f 60 


acres: 


Case (2) 


Ga 








1,043.000 






1,304,000 


Gn 








1,304,000 






1.304,000 


m. a. i 

r 








1,003 
60 






1,003 
60 


X 








50 






30 



Case (3) 

1,565,000 

1,304,000 

1,003 

60 

15 



It follows that: 



Case (I). Cut = 60,180+ ••^■^^■°°°-^'3°4.ooo^^^^g^ 

50 



Case (2), Cut = 6o.i8o + -'-3^^ig-"Q- ^'304.000 ^60,180 

30 
Case (3), Cut = 60.180 + ^ .565,000 - i.304.ooo ^ -- .g^ 

15 
In case (i) there was a deficit of growing stock, so the cut was reduced; in case 
(2) there was no change because the growing stock was normal; in case (3) there was 
an excess growing stock, so the allowed cut was largely increased and especialh^ because 
the excess was to be cut in 15 years. 

86. (4) Volume Regulation Based (on Growing Stock and) Size Classes 
(and Periods), (a) This so-called method* of 1883 as applied to selection 
forests of tolerant species is as follows: After inventory (by diameter classes). 
determine the rotation and the corresponding size of tree, then classify the 
stock in three classes: (i) Old zvood, trees more than two-thirds the exploit- 
able (rotation) size ; (2) Averai^e wood, trees less than two-thirds and more 
than one-third; (3) Young ivood, less than one-third (usually not calipered). 
Where there is a normal (or nearly normal) proportion of old and average wood 
(see discussion), the cut** equals the volume of the old wood divided by a third 
of the rotation plus half the annnal grozvth on the old zvood class zvhile it is 
being cut. 

87. Discussion of French Method of 1883. The method was designed for 
selection high ftjrests of tolerant species, where the regeneration could be 
secured in at least one-third the rotation, and where a sustained yield was 
important. It is based on the conception that a selection forest, normally 
constituted, is just like an even-aged forest (where, on equal areas, stands 
of all ages up to the rotation age are found), except that the various aged 
trees are intermingled. In the latter case an equal cut is secured by cutting 



* Based on the original official instructions issued by the French Secretary of Agri- 
culture and on the Chamonix Working Plan by A. S. Schaeffer. 

** Compare this method with the Hufnagl "diameter class method" described by Reck- 
nagel (ibid.), pp. 100-105; The Hufnagl method (Variation I) is: Annual cut =: volume 

■ of trees or of diameter classes years and over, plus increment thereof in - years."' 

2 4 

Recknagel gives an interesting example of (Variation 2) where tiie trees have been 

grouped by 3-inch classes with the basis data (for each class) of volume per tree. 

average number of trees per acre, and years required to grow from one class to the next 

(and "average age of the average tree in each diameter class). For each class the cut is 

equal to volume of class X number of trees per acre. The yield for all classes can then 

be increased or decreased according to the surplus or deficit in the growing stock. 

According to Recknagel's example the surplus is reduced in one cutting cycle, which 

is made equal to the number of years to grow to the highest diameter class from the 

preceding class. For more complete discussion see Recknagel. 



Volume MctJiods 



83 



each year areas of the same size and productivity. But in the selection forest 
the cutting must remove only ripe trees here and there over the entire area 
without any comparison of surface. Therefore, in this case volume must be 
substituted for surface. 

The method is based on the assumption (see diagram) that the volume of 
the old wood is y^ and the volume of the average wood ^ the total merchant- 
able volume, it being presumed that the young wood is unmerchantal)le. 











* 


C 


Q 










c 









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2 Q 


^ 

^ 

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According to the French Secretary of Agriculture, the data furnished by 
research on the mean annual rate of growth of high forests shows that this 
relationship is approximately as 5 is to 3. Therefore whenever in a selection 
forest the volume of the old wood and the average wood is as 5 is to 3, it 
can be taken for granted that these two groups are similar to the first two 
periodic blocks of a high forest. To demonstrate that the volume covering 
the two first periodic blocks of a regular high forest (divided into three 
periodic blocks) are about as 5 is to 3, which represents their average age 
respectively, it suffices to note that the trees of the second periodic block are 
the average wood, which has arrived at a state where the annual growth is 
very uniform and just about equal to the average of the stand and at a period 
when it is safe to figure the future growth as equal to the past average. 
Suppose a high forest with a 150-year rotation were divided into three periods 
of 50 years each. The average age of the first (old wood) and second 
(average wood) periodic blocks will be 125 and 75 years and will be separated 
by a length of time equal to a period of 50 years. In admitting that the future 
growth will be equal to the average growth, the volume of the 125-year 
wood will be equal to that of the 75-year old wood increased by an amount 



84 American Forest Regulation 

equal to 50 times the annual growth. Then if we designate the volume of 

the 75-year old wood as 3, the 125-year old \olume will be 3 -(- X 50 = 

3 -)- 2, or 5. This assumption of an equal mean annual growth, of course, is 
not exact, but according to French reasoning it is sufficiently accurate for 
an approximate foruiula, which is being continually revised at working plan 
revisions, when the standing timber is re-calipered. 

"One can object to this method of classification because the diameters are not exactly 
proportional to the ages, that they are not equal for the same species, or same age, 
inasmuch as the trees of a selection forest are very far from growing under the same 
conditions. But it is to be supposed that with a large number of trees .... a suffi- 
cient compensation will take place in order to even oflf the inaccuracies and render them 
negligible. Moreover it is not essential to arrive at exact mathematical results (nor 
possible)." 

The language and argument of the original French instructions is instructive 
in considering the method and in applying it. As originally promulgated, 
so as to be conservative, no increase was made in the cut for the growth 
which took place on the old wood while it was being harvested. But within 
recent years it is customary to figure growth. 

The method is simple when the proportion of the old wood to the young 
wood is as 5 is to 3, or nearly so, but this normal ratio is not usually found. 
Instead there is, 

(i) An excess of old wood, or 

(2) An excess of average wood. 
In either case (i) or (2) an approximately normal ratio is secured by trans- 
ferring diameter classes from the old wood to the average wood or vice versa 
if it is safe silviculturally to hold over some of the older trees or if (where 
the average wood is too great) the large average wood sizes can be cut without 
too great a sacrifice. 

An important feature of the application of this method by the best French 
working plan officers is that they compare the actual growing stock (on the 
basis of number of trees per acre of different sizes) with an empirical "normal" 
stand (an adjusted average for the region). This is an essential and important 
part of the method as best applied but is not mentioned in the official 
instructions. 

If desired, a rough area check can be applied by considering that the area 
cut over should be proportional to the volume removed. The original instruc- 
tions stipulated that (i) the length of the cutting period be a submultiple of 
a third of the rotation, (2) the number of compartments be about equal to 
the years in the period, (3) the local forester be free to allot the amount of 
the cut in each compartment according to local requirements at the time of 
cutting, and (4) the yield be revised at the end of each felling period. 

Disadvantages: 

(i) Unless there is some other check on the normality of the old wood 
and average wood besides the proportion of 5 to 3, it is insufficient because 
an acre might contain 5 board feet of old wood and 3 board feet of average 



Volume Mctlwds 



85 



wood without being normally constituted. There must be some conception 
of total volume. 

(2) Trees must be tallied down to 3^ the rotation age. 
Advantages: 

(i) The yield is in accordance with the condition of the stand. 

(2) The tendency is to work towards normal diameter classes. 

(3) A sustained yield is secured and the growing stock is being continually 
built up. 

(4) The method has worked fairly well in practice. 

88. Illustration* of French Method of 1883. The exploitable size is 24 inciies cor- 
responding to 180 years. 

The old wood is 17 inches and over, the average wood g to 16 inches inclusive and 
the young wood i to 8 inches. 

A sample inventory follows: 



• Y01 


ang wood 




Average wc 


)od 




Old wood 


D. B. H. 
inches 


Total 

Number volume 

trees bd. ft. 


D. B. H. 
inches 


Number 
trees 


Total 
volume 
bd. ft. 


D. B. H. 

inches 


Total 

Number volume 

trees bd. ft. 


I 

3 
4 
5 
6 

7 
8 


Not calipercd 
nor computed. 













9 
10 
II 
12 
13 
14 
IS 
16 



Completely 
calipered 
and computed 



Totals 



3,000 M 



17 
18 
19 
20 
21 
22 
23 



Completely 
calipered 
and 
computed 



5,000 M 



A. According to the inventory the normal proportion exists, the average wood 

totalling 3,000 M and the old wood 5,000 M; therefore, the cut is 5.ooo _g^ y^ p^^. ,,g^j. 

feo 

or if the old wood were growing at the rate of 2% per year. S.OOQ X -02 X 00 ^^ ^ ^j 

2 
would be added, making the cut 86 M. 

B. Suppose the volume of the old wood = 6,200 M, and 

the volume of the average wood := 1,800 M. 

Here the old wood exceeds the normal proportion so the old wood diameter classes 
should be examined to see if they can be transferred to the average wood group and 
held over a period equal to 60 years {Yi the rotation). If there is no objection to this 
transfer, the trees in the 17- and 18-inch diameter classes (which we will presume totals 



* An exact adaption of an official French illustration of the Method, but also based on 
the Chamonix Working Plan by A. Schaeffer. with American units substituted. 



86 Aincr'icaii Forest Rc<^uJation 

800 M) will be deducted from the old wood. Thus 6,200 M — Soo M = :^29, equals go M 

60 
(plus growth). 

C. Suppose tlic volume of the old wood = 3,300 M and 
the volume of the average wood = 4,700 M. 
11 Lie the average wood is in excess of the normal ratio so it is determined whether one 
or more of the largest average wood diameter classes can be transferred to the old 
wood for immediate cutting. If it is found that the 16-inch diameter class (which we 
will presume totals 600 M) can be added to the old wood, the volume will be 3,300 M 

plus 600 M, which equals 3,900 M, and the cut, '^ . equals 65 M (plus growth). 

60 

89. (5) Volume Regulation Based on the Tree as a Unit; (a) Indian 
Single Tree Method (Brandis''=). (CJf scientific interest, but might be used 
in the Philippines.) 

The forest is first ini'cntoried by broad diameter (in India = girth) classes, 
the current rate of diauieter growth determined, a technical rotation established, 
the mortality loss estimated, and finally the average number of trees maturing 
annually computed (by multiplying the trees in each class by the percentage that 
will survive) and the cut fixed so as to remove the surplus stock (or supply a 
deficiency) witJiin a reasonable period. (See illustration.) 

Discussion. The method originated in Burmese teak forests where the 
merchantable timber comprised but one tenth the stand. According to 
Schlich, 

". . . . Brandis's object was to ascertain as quickly as possible the number of first 
class teak trees which might be removed annually without exposing the forests to 
deterioration." * 

It must therefore be clear that the method is approximate and was designed 
simply to prevent overcutting in a tropical forest where but few species were 
merchantable. Since it deals with trees rather than a unit of measure, it is 
simple and easy of application in a country where low class labor must be 
used in valuation surveys. In recent** years, 

" The area check is applied by prescribing the order of the fellings through the 
different subdivisions (compartments) of the working circle. A table is drawn up 
showing for each year the subdvision on which the cut is to be located and number of 
trees to be removed." 

In the United States there appears to be no justification for the use of this 
method but it might be of value in the Philippines during the initial stages 
of forest management. 

The zveaknesscs of the so-called Brandis method are as follows: 

(i) The growth calculations are based on current growth in diameter, 
and in India particularly, this data is often scanty and unfortunately must be 
applied for considerable periods. 

(2) The mortality per cent is evidently a most essential part of the 
calculation, and yet according to the authors themselves, the basis for this 
mortality per cent is a mere guess. 



* This is based on Vol. Ill, Schlich's Manual of I'orestry, pp. ^-^-3-5- The illustra- 
tion is adapted directly but with added explanation. 

** Moore. Barrington, Methods for Regulating the Cut on National I'orests (P. S. A. F. 
igi2, p. 2~:). 



I'' ol 111 lie Methods 



87 



(3) The basis for determining the rotation is the length of time it takes 
a single tree to grow to a certain size. The factors of the mean annual volume 
])roduction per acre cannot be weighed — a most unfortunate feature in any 
rotation method. 

(4) Particularly wiicrc the forest is a mixed stand and where only one 
species in this stand is merchantable, there is grave question whether the 
younger age classes will survive a selection cutting which cuts one species 
which is merchantable and must leave less desirable species in possession of 
the ground. With this form of cutting the inference is that natural regener- 
ation of the desirable species will be unsatisfactory and therefore any method 
which counts on the survival of the desirable species now being lumbered is 
dangerous unless very frequent stock taking can be afforded. 

(5) The question of individual judgment is paramount, and different men 
might calculate a \astly dift'erent number of trees to cut. While this criticism 
is true in a certain measure of almost all yield calculations in their final 
analysis, and rightly so, yet in other methods the personal judgment is of 
less weight. 

The following might be cited as advantages: 

( i) It is suited for extensive tropical forests where only one or two species 
(such as teak) are merchantable and where crude selection felling is the rule. 

(2) Stock taking by native labor is possible owing to the use of broad 
diameter or circumference classes.* 

(3) Adapted for an initial check on cutting, where, because of economy, 
more modern methods cannot be applied. 

Illustration. The productive forest area is taken as 84,022 acres of 51 compartments. 
The field work showed: 



Class 

(D. B.H.) 

inches. 



Initial No. 

of trees 

(trees 

available). 



Total age 

(years) 

on entering 

class. 



Years to pass 

through 

each class. 



Percentage 
surviving 

and entering 
next class. 



1 

over 28 


31,523 
(29,947) 


156 




95 


II 
24-28 


18,114 
(15,397) 


130 


26 


85 


III 
18-24 


42,768 
(29,938) 


93 


37 


70 


IV 
12-18 


101,737 
(50,869) 


60 


33 


50 


V 
6-12 


150,910 
{37,72^) 


31 


29 


25 


Below 6 not counted. 


Totals 


345,052 
(163,879) 


156 


156 




Class II-V 


(133,932) 









* For a further discussion of this method see P. S. A. F., 1912, pp. 24-27 and Forestry 
Quarterly, p. 910, p. 52. and pp. 332-333 I" the Quarterly, p. 52, Class I should be 

«^>^ instead of '1>^. 



88 American Forest Regulation 

These figures are from a Burmese working plan by A. Roger. In the original plan 
column I was by girth classes. In column 2 the upper figure in each class is the result 
of the original stock taking and the bracketed figure the original stock multiplied by 
the percentage in column 5. 

Column 3 is based on the data in column 4 which is the result of stump analysis of 
only 198 trees. Column 5 — the crucial and important figures — is based on 

"observations made in this and other forests in Burma from which it was ascertained 
that the following percentages of sound trees are likely to survive and be available for 
utilization." 

The rotation was 160 years, 5 periods of 32 years each. It is clearly based on the 
number of years it takes a tree to grow up to the class V following 31 years to grow 
up to class I. 

90. (b) Diameter Limit (Pinchot-Graves). (Of scientific interest.) 
This metiiod (now abandoned by American foresters) is similar to the Indian 
single tree method in that it is based on current growth in diameter of single 
trees but with a volume unit for yield instead of the number of trees. It is 
of historical interest, only, and was first used in America in "The Adirondack 
Spruce" by Pinchot. Any method of regulation (unless the forest can be 
frequently re-estimated) based on current growth of individual trees is of 
little or doubtful value because of the uncertainty regarding the number 
of trees which pass from one diameter class to another (i.e., mortality per 
cent). It was described in France* as early as 1867 and is now only applied 
to beech selection coppice (taillis furete) chiefly in the Pyrenees. Huffel 
says that 

"such a system can evidently be applied only to forests very nearly normal. (This 
'normality' is rarely found.) In a fir stand rich in large trees, seedlings and saplings 
but poor in average sized trees, it would result in a short period of super-abundance, 
which would be followed by a period of largely reduced fellings or even by a complete 
suspension of income." 

Such a method is clearly unwise especially for virgin forests in the United 
States; nor is the Gazin** idea of more than scientific interest. 



* Huffel, Economie Forestiere, Vol. Ill, page 68. The term " of scientific interest" 
might be "of academic interest" throughout the text. 

** Stem Space Method {Gazin) (Of scientific interest). The stem space method of 
regulation is based on silviculture rather than on any mathematical formula. It is a 
silvicultural idea rather than a method that can be defined in a few words. Its basic 
features are: 

(i) Normal spacing of the boles without reference to form of stand. 

(2) To yield the maximum volume with the smallest growing stock by keeping the 
boles normally spaced. 

(3) The idea of rotation is done away ztnth. 

(4) The details are worked out on an average acre (normal in an empirical sense) 
and the treatment of the actual forest in hand patterned after it. 

The method (too intensive for present conditions in the United States) is of scien- 
tific interest because of the ideas it introduces, but it is of doubtful practicability until 
it has been successfully tried out and applied. Its advantages or disadvantages cannot 
be appraised as yet. (From Gazin. A., Le Traitement des Sapinieres base sur la notion 
d'lespacement des tiges, Paris, Imprimerie Lahure, 1902. pp. 1-17. Tlie metric system 
is used. Translation of this article may be studied in the 1917 Journal of Forestry.) 
See also § 83. 



Volume Methods 89 

91. Quiz. Define regulation of cut. 
What are three aims of regulating the cut? 
Explain why compromises are necessary. 
Explain the classification of methods of regulating the cut. 
What are the three main bases? 

Explain the main differences in regulating the forest on the main basis of (a) volume 
(b) area, and (c) area-volume (see Chapter IX). 

Give four bases of subdividing regulation on the basis of volume. 

What is the Von Mantel formula? its faults? its advantages? 

What is the Gurnaud idea? 

Is it a method of regulation? 

What is the basis of the Austrian formula? Explain it. 

Cite some peculiarities of the Austrian formula. Its advantages and disadvantages. 

Explain the French method of 1883. 

How was the formula derived? 

Illustrate its application to a selection forest. 

Is it customary to figure growth on the "old wood" while it is being cut? Why? 

What are the advantages and disadvantages of the method of 1883? 

Why is the Brandis single tree method unsuitable for the United States? 

What is the fundamental error in the Pinchot-Graves diameter limit scheme? 

Why is the Gazin scheme of no practical value? 



CHAPTER IX 
(B) AREA, AND (C) AREA-VOLUME METHODS OF REGULATION 

92. (B) Value and Classification of Area Methods. Proper regulation 
must take into consideration the \olunic, age, and area of a stand. Volume 
alone, as exemplified by the various formulae methods already described, is 
insufficient. Regulation by pure area alone is lacking in flexibility and does 
not consider sufficiently the essential factors of volume and changes of treat- 
ment necessitated by acts of Providence (such as windfall or disease). 

The inclusion of area allotment by periods under regulation by area tends 
to simplify the classification but is a departure from German procedure. 
Regulation on the basis of area (and age) has been classified as follows: 

Main basis, Secondary basis, 

(B) Area (and age). (i) Pure area. 

(2) Area allotment l)y periods. 

93. (i) Fixed Area as a Basis for Regulation of Cut. The simplest con- 
ception of pure area regulation is, the forest is divided into a number of cutting 
areas equal to the years in the rotation and one area is cut each year. Two mod- 
ifications of this basic plan may be necessary: (a) If the soil quality of the 
forest varies, then a proportionately larger area of the poorer sites must be 
laid out on the ground, (b) If the forest is so small that yearly logging is 
not justified, then the cutting areas are made proportionately larger to provide 
cutting every two, three, or more years as the circumstances require. 

Discussion. Regulation by fixed area may be of practical value in coppice 
forests or coppice under standards where regeneration is certain. It reight 
also be used in stands managed on a very short rotation and where the new 
crop is obtained by planting or sowing; a case in point would be the com- 
mercial production of Christmas trees. The fundamental idea of working 
o^■er equal areas each year or periodically is the basis for regulating cork 
oak production or resin crops, with the necessary silvical and commercial 
limitation on what cork is marketed or what trees are tapped for resin.* 

The European conception of fixed area regulation is to follow the order 
of cutting marked on the ground, but there is no practical reason why a stand, 
nearly ripe but damaged by fire, could not be cut ahead of its maturity. Shifts 
must then be yiadc and a corresixmding area licld ])ast maturity. 

Disadvantages: 

(i) The metliod is rigid and with a cliange in rotation or scheme of 



* .See French Forests and Forestry and Studies in French Forestrj\ both John Wiiey 
& Sons, for a discussion of cork, oak and resin regulation. 



Area and Arca-Voliunc Methods 91 

working, the whole forest must he redivided into entirely different cutting 
areas. 

(2) Forces cutting without considering the condition of the stand. 

Adz'a)ifai^es: 

(i) Easy to apply. 

(2) Equal annual or periodic cut and absolute regularity of age classes. 

94. Illustration of Fixed Area for Limiting the Cut. Given: Coppice forest of 100 
acres half on ridge (site III) and half in a valley (site I); rotation and cutting cycle 
20 years; annual cut required for constant fuel supply. Site I yields 20 cords at 20 
years and site III only 10 cords. 

If the soil value had been equal, the annual cutting areas would be — =: 5 acres; 

20 

but here half the stand is on a rocky ridge with one-half the soil value of the remainder; 
so the average reduced cutting area must take into consideration that the cut from two 
acres of the poor soil equals only one acre of the good soil. By a simple calculation 

(i.e., -— ^ - ^ =3-75 acres, and ^ =13 areas with 1.25 acres of site I left 

20 3.75 

over; on site III tlie cutting area would be double that of site I, i.e., 3-75X2 = 7.50, 

50 

and :r^ ^ 6 areas with 5 acres left over), the cutting areas are found to be as follows: 

for site I, 13 areas of 3.75 acres each; for site III 6 areas of 7.50 acres each. This 
would leave one area composed of 1.25 acres site I, and 5 acres site III, which would be 
equal in producing capacity to 2.50 acres of site I or a total of 3.75 acres (site I). The 
annual yield in cords would be obtained by multiplying 3.75 acres (site I) by 20 cords 
= 75 cords or on site III 7.50 acres X 10=75 cords, which is an identical figure. 

95. (2) Area Allotment by Periods as a Basis for Regulation.* An allot- 
ment method — 7«;7it'n a rotation is fixed and for a given year or period of rotation 
a certain area is allotted to he cut. 

Discussion. This is somewhat similar to regulation by pure area (with 
fixed cutting areas) but decidedly less rigid and differs in that the cutting 
areas are not permanently fixed on the ground in the order of cutting but 
instead compartments or lots are allotted to the various periods of the rota- 
tion. These periods are 10 to 30 years in length and the total number depends 
on the length of the rotation. The stands allotted to the first period are,** 

"measured, their volume calculated, and the increment for half the number of j^ears 
in the period added. The total of the volume thus obtained is divided by the number 
of years in the period .... to obtain the average of the final annual yield during the 
first period .... thinnings must be added." 

As a matter of fact, in the modern European working plan allotments are 
only recorded for one, or at most two, periods. Since the working plan will 
be revised at the end of the period, it is unnecessary to make permanent 
allotments far ahead because changed conditions may force a complete 
change; it is for this reason Judeich originated his stand selection method 
(see par. ioo\. 

It must be clear that 1)efore indixidual stands (which may be allotted) are 
cut the growth continues on the uncut growing stock in these stands. After 



* See Schlich, \"ol. III. 3d Edition, p. 311. 
** Ibid., p. 313. 



92 American Forest Regulation 

the cutting^, regeneration and development of the seedHngs goes on, but there 
is no immediate tangible merchantal)le increment. If, for example, 20 stands 
are allotted to a 20-year period, then after the first year 19 stands will be 
growing while at the beginning of the 20th year only one stand will remain. 
This explains why in all methods of regulation dealing with indi\idual stands 
or age classes (as in the French method of 1883) half the growth is added 
to the estimated yield of the stands to be cut. 

To sum up, there is no reason for using area allotment when better results 
can be obtained by taking into consideration volume and "stand selection." 
Even in Prussia the area allotment was only used for Aery regular stands. 

Disadvantages: 

(i) Age class distribution may be neglected in first rotation. 

(2) Surplus growing stock is not reduced, and immature stands may l)e 
sacrificed. 

Advantages: 

(i) It is simple and easily applied in the office, and tends to quickly 
estjiblish the normal distribution of age classes. 

Illustration. Since the method is not recommended, no original illustration is given. 
Those interested in seeing how the method is applied in Europe are referred to pages 
382-387 Schlich, Vol. Ill, 3d edition. Here it will be noted that after the various stands 
are allotted to each of the five periods, there is still a considerable variation in the 
areas to be cut over; namely, in round figures 30, 34, 33, 2>2^ and 30^^ acres, the mean 
area of the period being 32.03 acres. The smaller the lots, the more accurate the area 
equalization for each period. The period in the illustration is 20 years, so the age of 
the stands listed for cutting are taken not at the beginning of the period but to the 
middle of the period (i.e., age at beginning of period plus 10 years). The yield is then 
read from the yield table for tlie species and age and then multiplied by the number of 
acres; this procedure of taking the yield to the middle of the period obviates making a 
separate calculation for growth. The estimated yield from thinnings is then added. 

96. Use of Yield Tables in Computing Volumes. When using yield tables 
with a period (or stand) method of regulation, it is often convenient to reduce 
a yield table which is fully stocked to terms of the stand which is not fully 
stocked. This is done by comparing the average stand volume per acre 
with the volume per acre given in the yield table. Before making the com- 
parison, it is of course necessary to obtain the average age of the stand either 
by sample trees or on the basis of the age of the tree corresponding to the 
average diameter. For example, suppose the mature age class 200 years 
old averaged 8,375 feet per acre and the yield table 16,750, then in reading 
future empirical yields to apply on the forest all figures in the yield table 
are reduced one half, because, 

s^and __ 8,375 ^^ 
yield table 16,750' ^^' 

When long j^eriods are used in calculations, it may be advisable to compute 
the cut by the weighted yield table formula instead of computing the cut by 
(a) reading to the middle of the period in the yield table or by (b) reading 



Area and Area-V olnme Methods 93 

from the yield table to the first year of the period and then adding half the 
growth. The weighted yield table method merely recognized that the mean 
annual growth is a curve and not a straight line and is fully explained in the 
Journal of Forestry.* 

97. (C) Area-Volume (and Age) Basis of Regulation— Value and Clas- 
sification, Volume alone is not a satisfactory basis for regulation, nor is age 
and area alone, because in the latter case the factor of volume is omitted as 
a primary determining factor. It is clear then that the ideal of regulation is 
to consider area, volume and age. Taken together they constitute the essen- 
tials to be considered in regulating a forest, while singly they are simply 
important, but not determining, factors. As many writers point out, and 
as has been repeatedly emphasized in this book, the old fashioned idea of 
allotment to all periods of the rotation is generally abandoned. With this 
modification there is not such a vital difference between (i) and (2) given 
below. Regulation on the basis of area-volume (and age) has been classified 
as follows : 

Main basis, Secondary basis, 

(C) Area-volume (and age). (i) Volume and area-volume (age) 

allotment by periods. 

(2) Stand selection. 

(3) Cutting cycles and felling re- 
serve (see part II). 

98. (i) Volume and Area-volume (and Age) Allotment as a Basis for 
Regulation. The definition is similar to that for area allotments by periods: 
When a rotation is fixed and for a given year or period of the rotation a certain 
area or a certain amount of stock is allotted to be cut. 

Discussion. The so-called volume allotment method has not been separately 
discussed because it possesses no advantage over the method of periods by 
area and volume combined. In volume allotment by periods the chief aim 
is to equalize the volume rather than the area (see §95). Volume allotment 
as practiced in Europe is illustrated by Schlich, Vol. Ill, 3d Edition, page 
388. Volume allotment was the dominant method in Prussia during the 
19th century but is now replaced by volume-area allotment with a view to 
age class distribution and felling series. With area-volume allotments the 
areas and volumes allotted to the first period are divided by the years in the 
period to obtain the area to be cut over and the volume which will be secured 
from the main fellings. Then the aggregate of individual stands is either 
increased or diminished according to the areas and volumes (and ages) of the 
areas which should be felled. The goal is regulation on the basis of the 
individual compartments, and the smaller the stand (lot), the more equalized 
is the estimate of volume and the more intensive the regulation. Taking into 
consideration and weighing both area and volume gives somewhat similar 
results to area allotment but with a very careful check on the site quality of 



* Woolsey, T. S., Jr., Computing Volumes in Period Allotment. (J. of F.. 1917, pp. 
431-434.) 



94 American Forest Regulation 

each lot gauged by volume. The choice of the stands to be allotted depends 
on maturity (and age), their relation to the felling series, a sustained yield 
and the regeneration of the most desirable and suitable species. 

Disadvantages: 

(i) Equalization and allotment of both area and volume is a difficult task. 

(2) Suitable grouping of age classes is difficult. 

(3) Cuts of equal area and volume are not desirable if stands of over- 
mature timber must be held over or young timber sacrificed. 

(4) It possesses no clear cut ad\antage over the stand method described 
in § 100. 

Advantages: 

(i) It trains the working plans officer to think in terms of age, area 
and volume. 

(2) If broadly applied it may result in a good distribution of age classes 
and cutting series,* as well as a sustained yield and is very similar to the 
stand selection. 

Illitslration. Since this method is better iitted for European forests which have 
already been regulated under working plans, the student is referred to Schlich's Vol. 
Ill (p. 382 and 388) for examples of area and volume allotment. See also § loi. 

99. Modern Allotment Principles. From a review of the modern allot- 
ment methods used in the various German states the following principles 
appear to have been evolved after years of regulation practice : 

(i) Area allotment is used only for simple regular stands; combined 
allotment (volume and area) is preferred for irregular stands. 

(2) Yield calculations are usually recorded only for the first period, though 
sometimes calculated for more as a trial balance. 

(3) The age class table is the most important basis of the working plan 
for a timber forest ; in mixed stands areas are classified proportionately, and 
in selection forests estimated carefully, considering age or size class relations. 

, . ™, , . ,. • . total area divided bv number of periods 

(4) i he normal ijcnodic area, i.e.. ~ -. — -. 

years in period 

is the basis for the cut determination. If excess of mature stands occur, 
more than the normal area (and vice versa) may be allotted. 

(5) Trees of main cut are calipered ; intermediate cut estimated. Thin- 
nings regulated by area and their yield estimated. The periods are usually 
20 years. 

(6) Revisions of the cut calculations usually take place every 10 years. 

(7) The assignment of compartments or lots to the first period depends 



* It is taken for granted that the silvical needs for a proper cutting series are thor- 
oughly understood and that under intensive forestrj' the age of the bordering stands 
must be planned long in advance 



Area and Arca-Volitiiic MctJiods 95 

on the condition of each stand, felling series, age class relation and natural 
phenomena, as well as area and volume. 

100. Regulation by (Americanized) Stand Selection (after Judeich). The 
stand (or individualizing) methods may be defined as follows : Each stand is 
investigated for its maturity and designated for cutting provided other age classes 
are in existence to assure continuity of crops. 

Schlich rightly considers "financial maturity" too narrow a conception of 
stand selection because the object of management may not be solely financial 
considerations. Actual practice in Europe seems to justify his position, 
because the selection of stands to be cut depends on a number of factors ; 
namely, (i) Financial maturity, (2) Technical or administrative needs, (3) 
Maturity judged by local age, soil and stand conditions, (4) Poor growth, 
(5) Felling series, full increment and normal conditions generally. 

Roth calls this method "limited area allotment" and classes it as an area 
allotment for the first period only, while Schlich emphasizes the selection of 
stands for cutting on silvicultural grounds or objects of management. The 
forest certainly progresses toward the normal if the method is intelligently 
applied. Roth says (p. 145) that, 

"It is usuallj' claimed that this method only binds the action for the coming ten or 
twenty years, while regular area allotment is claimed to be binding for an entire 
rotation. This is not true." 

Roth is correct; paper work tabulation today would never be binding over 
re\ision periods. 

The amount to cut depends (in Europe) partly on the results of former 
working plans and partly on an area-volume check. No considerable error 
in over-cutting or under-cutting is likely with careful revisions every 10 to 
20 years. To sum up, the cutting of stands is according to local requirements 
checked at frequent intervals. 

Disadvantages: (i) Stands may become mixed as to age class arrange- 
ment owing to the freedom allowed in selecting stands. 

(2) The sustained yield may be departed from if too much freedom is 
given to selections for cutting solely on silvicultural grounds. 

Advantages: (i) The method is supple and broad gauge. 

(2) It can be readily applied under many existing American conditions. 

loi. Illustration of Stand Selection in Eastern and Western Forests. A. Eastern 
Forest. Given: Irregular lots or compartments of white pine, old field spruce, and 
mixed hardwoods in Northern New England, with an excellent market (except for 
pine-spruce cordwood) and sufficient transportation. The white pine is to be naturally 
regenerated after clear cutting and the old field spruce clear cut and replanted. The 
mixed hardwoods are to be retained as hardwood stands and are in need of heavy 
improvement fellings for the first 30 years of the rotation, which has been fixed tenta- 
tively at 80 years with the expectation of a reduction to 70 or 60 years after 20-40 years. 
.\fter stock taking the lots were tabulated as given below. It must be realized, however, 
that within the lots there is considerable variation in age Except for the small scenic 
lot, the object of management is to obtain the best financial returns compatible with a 
reasonably sustained yield. A small local sawmill is largely dependent on the forest for 
logs; the high grade logs are shipped by rail to a larger mill. The resident forester is 
also manager of some 25,000 acres additional so must systematize his business. The 
timber is designated or marked for cutting under his direction and the logging done by 
contract with penalties for damage to reproduction or standing timber and for waste 
in logging. 



g6 A)ncrican forest Regulation 

Estimated volume** 
Lot Area Age Forest* M. Board 

No. Acres Class Type Feet Cords Remarks. 

(1) (2) (3) (4) (5) (6) (7) (8) 



I 


lO 


90 


p 


I 


I. 


850 




2 


42 


30 


H 


2 


.66 




560 


3 


II 


lOO 


p 


2 


.70 


600 




4 


8 


120 


H 


I 


.90 


(100) 


(580) 


S 


i6 


6o 


P 


2 


.90 


680 




6 


15 


40 


s 




1. 


300 




7 


21 


70 


P 


2 


•50 


590 




8 


8i 


20 


P 


2 


I. 






9 


20 


70 


PH 


[ 


■50 


560 




10 


10 


100 


P 


2 


.80 


620 




II 


6 


80 


H 


2 


.60 


30 


130 


12 


33 


50 


P 


2 


.70 


■850 




13 


24 


60 


S 




.90 


650 




14 


25 


50 


P 


2 


.70 


640 




15 


17 


60 


P 


2 


•50 


400 




i6 


12 


30 


P 


3 


.60 


100 




17 


i8 


40 


P 


H 


.80 


470 




i8 


6o 


30 


P 


2 


.50 


154 




19 


30 


so 


P 


3 


.80 


580 




20 


25 


30 


P 


I 


.70 


243 




21 


35 


60 


P 


2 


.■^o 


820 




22 


36 


80 


S 




.80 


1,150 




23 


28 


60 


H 


2 


.90 


120 


710 


24 


45 


40 


P 


2 


■ 70 


740 




25 


6o 


20 


P 


I 


I. 


270 




26 


45 


50 


s 




.80 


900 




27 


32 


40 


P 


3 


.70 


320 




28 


100 





H 


3 


.20 






29 


75 


50 


P 


3 


•50 


900 




30 


6o 


20 


P 


H 


.80 


220 





Thrifty, good increment. 

Fungus infected. 

Scenic forest reserved for park. 

Rapid growth & still very thrifty. 

Needs thinning. 

Hardwoods in openings. 

Fully stocked, thrifty. 

Open stand. 

Mature, needs cutting. 

One fourth stand dead chestnut. 

Fine thrifty stand. 

Poorly pruned. 



Ridge, slow growth. 

Some windfall or snowbrake. 

Trees stunted due to lack of 

(thinnings. 

Planted in 1900, very regular. 
Some windfall. 
5 acres fire killed. 
Burned over 1919. 
Birch in openings. 
Very wet soil, liable to windfall. 
— (Scenic forest not added in 
Totals 1,000 13,750 1,400 totals.) 

Before making a decision what to cut during the next 20 years, a number of factors 
must be carefully weighed. The figures are approximations only for purposes of illustration. 

(i) Age classes. Dividing the forest into four age classes of 20 years each, we have 
the following acres in each class: 

"I Period" "IT Period" "III Period" "IV Period" 

61-80 years and over 41-60 years 21-30 years 1-20 years 

122 acres 328 acres 249 acres 301 acres 

T^i ii , -J- „ ■ 1000 

Ihe normal periodic area is ^^ X 20 = 250 acres, or i2>/> acres per year. Thus the 

III period is nearly normal, while I is very deficient. 

(2) Growth. For an approximation of hardwood volumes and growth the basis is 
as follows: Hardwood quality i, i cord per acre per j^ear (if fully stocked); hardwood 
quality II. .7 per acre per year; hardwood quality III, .3 per acre per j'ear. It is pre- 
sumed from local data that y^ the hardwood yield in stands 50 years or over will be 
board feet and 7/3 cordwood. White pine growth is from Bulletin 13, Forest Service. 
The spruce if fully stocked is estimated at 500 board feet per acre per year. The actual 
mean annual growth on the whole forest is estimated at 250,000 ft. (from table 7 
Forest Service Bulletin 13, already referred to; reduced to conform with per cent 
stocked). The normal growth should be about 360,000 ft. B.M. (cordw-ood excluded). 

(3) Growing stock. The actual growing stock, reduced to a common factor of 
board feet (counting 3 cords as equal to i.ooo board feet, obviously a rule of thumb 
ratio based on local conditions) is 13,750 M ft. B. M. and 1,400 cords or total of 14.216 ^'kl 
ft. B. M. This is based on actual calipering on 20% of the area -where over 30 years 



* Key to aI)breviations used: P H := Pine and Hemlock; H i == Hardwoods Site i; 
H 2= Hardwoods Site II; H 3 — Hardwoods Site III; S = Pure Spruce; P i = Pure 
Pine Site I; P 2 = Pure Pine Site II. 

** From tables for white pine, page 23. Bull. 13, I'orest Service, figures evened off. 



Area and Area-Volume Methods 97 

old aud on ocular guesses in stands 30 years and under. It is clear that the hardwood 
cordwood problem is not a serious one, since it can be sold locally on the cutting areas. 
The normal growing stock (estimated by one of the methods already described) 
should be 1 4.400 M ft. for a rotation of 80 years; the apparent approach to normality 
of the actual growing stock is because there are stands past the rotation age with high 
yields per acre. 

(4) Cutting scries is not considered except that in the spruce stands a shelter belt 
of pine or hardwoods is left on the N. W. to protect the spruce from the heavy spring 
wind storms so frequent in the locality. 

(5) Hoii' much to cut? Where to cut? Because it is likely that the growing stock 
will be decreased (since it is anticipated that the rotation will be decreased from 80 to 
60 years within the next 40 years), it is proposed to cut the following lots (cutting order 
to be left to local forester) from 1920-1940 which it is estimated will yield the amounts 
shown : 

Av. age Yield 

Lot No. Acres when cut M. bd. ft. cords Reason for cutting. 

I ID 100 850 .. Should be cut last since growth 

excellent. 
Needs cutting, fungus infected. 
10 Dying and down timber only to be 

cut. 
Open stand with advance regenera- 
tion, part of area needs replanting. 
Open stand. 
Fully mature. 
130 Dead chestnut will be lost unless 

cut at once. 
22 2^ 90 1. 1 50 .. Growth very slow. 

Totals 122 4,420 I40± 



3 
4 


II 
8 


no 
130 


600 
20 


7 


21 


80 


590 


9 
10 
II 


20 

10 

6 


80 

no 

90 


560 

620 

30 



Per year 6.1 



Apparently the area cut over is too small and the age class distribution will be dis- 
arranged, but it should be noted that lot No. 28 has just been burned over and com- 
prises TOO acres, which plus 122 -=-20^ an annual cut of 11. i acres while the normal 
area is 12.5. The volume to be cut comprises favorably with the mean annual growth: 
i.e., 221,000 of main cut plus half the growth of the stands cut for 20 years or about 
26 M and an estimated 2 M ft. per year from thinnings or a total of 249,000 ft. B. M. 
In case there was considerable doubt about the advisability of increasing the cut, so 
as to allow cutting other stands which were overmature and declining in vigor, proper 
technique would probably justify largely exceeding the mean annual growth. It should 
nevertheless be recognized that in New England stumpage prices may double or 
treble thirty years from now when the bulk of the best timber used must be transported 
from the Pacific Coast. This is an argument for retaming a stand (such as is found in 
Lot i) that is growing thriftily, notwithstanding the fact it is well over the rotation 
age. In this instance further checks are hardly necessary but might be applied before 
reaching a decision on the cut. It must be emphasized that the answer given to 
this particular problem is not necessarily the one and only correct solution. A good 
deal would depend on the minute local circumstances. But in any case, it is clear 
from the table of lots that there will be ample merchantable timber for future cutting 
after 20 j^ears have elapsed. 

As a further illustration of the broad application of the stand method to a forest 
actually under management for more than 10 years, reference is made to appendix B 
and especially to the tabular summary of forest types by area and age given in Bulletin 
No. I, Harvard Forest. In 1909 Professor Fisher estimated the mean annual incre- 
ment on the Harvard Forest at about 250,000 board feet and cut that amount for ten 
years, i.e., 2,500,000 feet. The estimated growing stock in 1919 was 12,435,000 and only 
10,500,000 in 1909, an increase of 1,935,000 which plus 2,500,000, the amount cut, gives 
a total of 4,435,000-4-10 years = 443,500 ft. B. M.; so the cutting of only 250,000 was 
clearly very conservative and the forest is being enriched and built up. But part of 
the increase is perhaps due to trees (which had no board foot value) reaching merchant- 
able size through increase in diameter. The clever classification by forest types sub- 
divided into "tracts" and age classes is worthy of adoption under similar conditions. 

B. ircstcrn Forest. Let us suppose that in 1920 an Arizona western yellow pine 
forest of 10,000 acres (within a National Forest) is divided into four age classes which 
could be approximately separated and mapped (based on strip surveys for 10% of area) 
as follows: 



gS American forest Regulation 



Area 
Age Class Age Limits Acres Per Acre Total 

(I) (2) (3) (4) (5)_ 

200-360 



(A) Overmature (m erchantable) 300 4,ooo 10.000 40,ooo 

240-199 

(B) Mature (merch antable) 180 2,000 12,000 24,000 

20-139 

(C) Immature (^ merchantable) lOO 2,000 7,000 14.000 

(D) Reproduction (no merchant- 

able trees) 1-19 2,000 o o^ 

Totals 10,000 78,000 M 

This condition is typical of many forest areas in the United States but class (A) and 
(B) would be usually grouped as one overmature age class, and an accurate separation 
of age classes is often impossible (see Part II of this book). 

The established rotation is 200 years. A local sawmill (cutting 8,000 M per year) 
must be supplied with timber under practical logging conditions, and it is desired to 
retain the sawmill as a permanent local industry. Dividing the total stand (column 
5) 78.000 M by the area (column 3), we have an average stand of 7,800 ft. per acre or 
4,992 M per section (640 acres) which must be completely logged over to make sure of 
cutting all the overmature timber. Since the logging (owing to silvicultural factors) 
must remove all the overmature timber, about 80% of the mature and 10% of the 
immature (thinnings and improvement cutting of diseased trees), the average cut per 
acre will be 4,000+ 1,920+ 140 board feet or a total of 6,060 and will leave uncut 1,740 
feet B. M. 

From extensive sample plots on land cut over under existing conditions we know 
that the growth is approximately from 41 to 141 board feet per acre depending on the 
percentage of immature stands of rapid growth. As a rule of thumb figure 

41ZLL4^ =91, or say 100 board feet may be assumed. On 10,000 acres of cut over 
2 

land the current growth would be about 1.000,000 feet per year. Dividing 10,000 by the 

rotation age, ^°'°°° = 50 acres to be cut each year. Assuming 6,060 as the cut. we 
200 

have 6.060 X 50 = 303,000 board feet, which is less than Vs the estimated current growth 
after logging (if the whole tract were rapidly cut over, say within 5 years). There is 
a further complication in that the rotation may later on be reduced to froni 140 to 
160 years owing to protection from fire, sheep grazing and the judicious thinning of 
immature stands. Moreover, under present conditions it is assumed practical logging 
requires a cut of at least 2^^ million bd. ft. per section (640 acresj or about 4,000 ft. 
per acre. . 

JVhat annual cut should be allowed? Classes (A) and (B) cover 6,000 acres and contain 
64,000 M feet. The 10% cut from class (C) is omitted from consideration since the 
cut of 140 board feet additional is practically immaterial to the answer. The slower 
the rate of cutting, the greater the losses from death, windfall, misletoe, etc. in classes 
(A) and (B), but the greater the hiatus in cut, when this overmature stock is removed. 

Case (a), If (A) and (B) are cut in 10 years the annual cut is 5.920,000+ thinnings, 

(b), " " " " " " " 20 " " " " " 2,960,000 + 

(c), " " " " " " " 30 •' " " " " 1,973,000 + 

(d), " " " " ■' " " 40 " " " " " 1,480,000 + 

If class (A) only were cut the yield would be 4,000 M if cut in 10 years, 2,000 M if cut 
in 30 years, 1,000 M in 40 years; with thinnings added in each case. Cutting trees in 
class (A) in 20 years the cut per acre would be 4.000 ft. our minimum logging require- 
ment. Ten years is certainly too short a period and 40 too long because class (A) 
will suffer through death and disease. The choice then lies between 20 or 30 years. 
The final choice we will assume should be 20 years because it prolongs the cut. gives 
an ample cut per acre, and by commencing sales in areas where most of the over- 
mature timber is found, the loss through overmaturity is minimized. Moreover, it 
is possible to cover the whole transaction in a 20-year timber sale. 

(Solution No. i). The cut will then be, 2.960.000 (from A & B) + 70,000 (from C) = 
3,030.000 per year (500 acres or 2/$ the necessary supply to run the mill). The govern- 
ing factors have been overmaturity of timber which has necessitated cutting 10 times 
the normal area of 50 acres (or 7I/2 times even if the rotation were reduced to 150 



Area and Area-Volume Methods 99 

years). The decision, obviously a compromise, is wise silviculturally and economically, 
but from the regulation standpoint leaves much to be desired. It omits any attempt to be 
exact as to loss from decadence, growth during 20 years cutting period, etc. since it 
does not appear necessary to have more exact figures. If yield tables are made, the 
figures of decadence and growth are easily approximated. One of two things must 
then be done. The mil! must buy private timber or the governrnent must increase the 
size of the working circle to about 263.^ thousand acres with the understanding that at 
the end of 20 years (1940) tlie capacity of the mill must be reduced to the capacity of the 
forest — a- reasonable restriction. It is even possible that in 1940 the character of 
logging will have changed and the logging railroad in use will be scraped and 
the logging conducted by small gasoline mills with motor transport. In other words. 
the 8,000 M cut of the present mill should not influence the solution of the problem 
after 1940. 

Solution No. i is based on a compromise clearly recognizing the necessity of a com- 
plete readjustment after the overmature timber is salvaged. If there were no additional 
private or public stumpage available and if the mill would be forced to shut down on a 
cut of 3 million per year (but could operate on 6 million) the cutting of class (A) and 
(B) might have to be sanctioned in 10 years. The problem as solved is really on the 
basis of the Americanized stand method and without holding overmature timber so as 
to equalize the cut 20 years from now — a transition period of cutting is frankly acknowl- 
edged as a necessity to prevent loss through decadence. The preliminary cutting cycle 
is 20 years. It should be clearly noted what the age class and stand condition will be 
at the end of 20 years if this solution of tlie cut is adopted. For the sake of simplicity, 
the arrangement of age classes already used is followed: 

Age Class Age Limits Area Volume Board Feet 

Per acre Total 

A 0-19 4,000 o o 

B 160-219 2,000 2,880* ^ 5,760,000 

C 40-159 2,000 9,000*** 18,000,000 

D 20-39 2,000 1,000** 2,000,000 

Totals 10,000 25,760,000 

Had class B been uncut, the stand in 1940 would have been about 45 million, a far 
preferable figure from the standpoint of regulation and much better adapted to continue 
a reasonably sustained yield. But in the example given this was sacrificed to give a 
larger cut per acre and to avoid loss in mature timber. 

The fundamental error made by some foresters in their calculations is that they 
assume that the answer today must be completely and logically worked out for con- 
ditions 20 to 50 years from now, which it is reasonable to suppose will be totally 
different and unquestionably much more intensive than we can bring ourselves to realise. 
Compare forest conditions in 1870 with those of 1920 and see what a great change is in 
effect. 

(Solution No. 2.) Now suppose that the working plans officer wanted to make sorne 
sacrifice in order to ensure a better sustained yield in the future and so as to avoid 
the hiatus or lack of merchantable stands, which would occur with solution No. i. Let 
us further suppose that the normal growing stock on 10,000 acres averages 7,000 feet 
per acre or a totai of 70,000 M ft. By comparing this 70,000 M ft. with the total of 
column (5) in the first table, it is seen there is an apparent surplus of 8,000 M ft. But 
considering there is 40,000 M of overmature timber (age class A), it is evident that even 
today a deficit in real producing capacity actually exists, and a very serious one. In 
solution No. i we cut 6,060 feet per acre or 777o and left 1,740 feet or 23%. Granted 
we could change our silvicultural methods, let us see what we could do to secure a 
better sustained yield in the future by the following plan: cut all of {K), 20% of (B) 
and 10% of (C) as before. Make the cutting cycle 30 years. Our cut would then be 
(figures evened off) as follows: 

2 

40,000 M — H(2.8io** feet X 4,000 acres) -{- — (24,000 M)* 

-j- J^ ( X 2,000 X 2,000 acres) +-(i4>ooo M) =40.980 M -^ 30 years 
10 10 

= 1,366 M per year (this solution thus gives less than half the yield given in plan 



* 2% per year growth added to 20% of 12,000 ft. per acre. This figure however had 
best be obtained from yield table. 

** Read from yield table. S% cut in thinnings, etc. is not deducted because this is 
pure gain (being saved from loss). 

*** A loss here from 10 M per acre to 7,190 board feet over a period of 30 years. 

* Growth from 12 M per acre to 14 M. 



loo A})icrica)i Forest Regulation 

XT \ T- . ^ 1- o 1 . .1 ^- 1.366 8.0CM3 

No. i). To yet our cut ot 8,000 per year, we adopt tlie equation — ^ := whi.-li 

10,000 X • ^^'"^" 

when solved for x gives an answer of 60,000 acres in round figures, for the working 

circle. Now if we cut as indicated commencing in 1920, the condition of the forest in 

1950 will be as follows: 



Age class 


Age 


Area 
acres 

(3) 


Per acre 
year 1950 

(4) 


Total 


(I) 


(2) 


(5) 


A 
B 
C 
D 


1-20 


4,400 
1,600 
2,000 


14,000 

2,000 

10.000 




15 
170-229 




210 

50-169 

130 
30-49 


22,400 
4,000 


40 


20,000 






10,000 




46,000 M ft. 



In this case we have cut 4H M per acre removing but 57% of the stand but the stand 
is left in a much better shape for regulation and probably for regeneration, and we 
have only lost 4.8 million feet from decay, etc. in Class (A). This loss will perhaps 
be more than made up by an increase in stumpage price. Yet our growing stock is 
still much less than normal. With 4/10 the forest stocked with an overmature stand, 
it would be unwise to try to bridge the gap made by our getting rid of the overmature 
Class (A). This solution No. 2 is better than solution No. i judged from the stand- 
point of future regulation. Yet even in this case we are left after the first cutting 
cycle with insufificient growing stock and too many young age classes. We will have 
0-50 years, 64%; 51-100 years, o: 101-50, 20%: and 151-200. o, but 16% at the age of 
210. This is typical of the age class confusion that results after cutting in virgin stands 
even when "conservative logging" is followed. Were it possible to reduce the rotation 
to 150 years, then the situation would be less serious, and even as it stands, it will be 
possil)le to w'hip the forest into more normal condition as the rotation proceeds. 

102. Differences between Area-volume Allotment and Stand Method/'' As 
originally ii.sed the area-volnme allotment recorded the areas and amounts 
for all the periods. Today allotments are usually made only for the first, or 
at most the second period. In other words, it approaches the stand method, 
where the cutting is arranged for 10 to 20 years only. In making allotments, 
the main stress is on equal areas and equal volumes to be cut in each period. 
With the stand method the main objective is to select stands in financial or 
technical need of cutting. Another difference is that the yield in the allot- 
ment method is largely based on a comparison of areas and volumes, while 
in stand selection the cut may be based on equal cutting areas, on mean 



* In Oregon it is likely (according to Weidman) that clear cutting of western j^ellow 
pine to free the advance regeneration would be a sound silvicultural sj'stem. A few 
seed trees may be retained on the chance that fire might destroy the existing young 
growth. It is therefore anticipated that the present system of periodic cuts every 50 
or 60 years in the many-aged yellow pine climax type will be abandoned, because the 
next crop will be even-aged. Under these conditions how will a sustained yield be 
secured? The problem is readily solved, (a) Divide the working circle into convenient 
compartments, (b) Decide on the rotation, (c) Adopt a cutting cycle, (d) Cut the 
most mature' timber first, (e) Regulate the cut by allotment to periods (or by the 
stand method) frankly admitting that the present yield is preliminary and must be 
radically readjusted when the (excess) mature growing stock is removed. 



Area and Area-Volume Methods loi 

annual growth if the age class distribution is fairly normal, or on any estab- 
lished method of gauging the cut. 

Formerly there was thus the rigid allotment "framework" but today the 
allotment and stand methods tend to become more and more similar. 

103. Use of Age Classes in Regulation. The various Hufnagl methods 
(described in detail by Recknagel in his "Forest Working Plans" (pp. 100, 
108, no) ) are of interest, since they introduce new ideas of regulation, but 
usually the problem will be reduced in the final analysis to using the stand 
method with allotments of age classes to the current cutting cycle or (if the 
age class distribution happened to be fairly normal) to the proportionate share 
of the rotation, as with the French method of 1883. Even in American 
selection forests, empirical age classes may be distinguished and separated 
by correlating age with diameter as given in § 160, and then the age class 
can be allotted for cutting as if a distinct stand. This plan was the basis 
for Professor Chapman's so-called "American Method" as it was first devised 
(see part II for present revised "American Method of Horizontal Cut"). 

It is of value to remember that in uneven age stands; (i) the volume of 
one or more mature age classes chosen for cutting divided by the (a) years 
of the cutting cycle or (b) their proportionate share of the years in the 
rotation or (c) years in the period to which these mature age classes are 
allotted for cutting, gives an indication of what can be cut. 

(2) The volume of one or more mature age classes chosen for cutting, 
divided by the area they occupy, gives the average cut per acre; and if 
multiplied by the mean area to be cut over gives an indicated check on the 
volume that can be cut under given conditions. 

(3) The normality or abnormality of age classes, after their average age 
and volume is obtained, can be checked by comparing the areas they occupy. 
The relative area occupied by the merchantable age classes is obtained by 
dividing their actual total volume by the empirical yield table figure for the 
same age (see chapter XII). 

(4) When age classes are allotted for cutting, a figure equal to half the 
growth (or loss through decadence) while they are being cut should be added 
to (or subtracted from) their volume. Owing to the generally unknown and 
uncertain factor of natural loss of numbers in forest stands, it is dangerous 
to apply current growth to diameter classes in order to compute future 
growth except for very short periods, followed by stock taking and a read- 
justment of figures. 

104. Regulation on Basis of Cutting Cycles and Felling Reserve. The 
so-called "American method" is defined by Professor Chapman as follows : 
Determination and equalization of the annual cut on basis of volume, by means 
of varying the length of the first and second cutting cycles, and determination of 
the actual annual cut by using the principle of a felling reserve and cutting series, 
instead of an allotment of areas or stands for cutting tvithin the period. 

Discussion. The whole of Part II of this volume is devoted to a very 
detailed treatise on the foundations of the "American method," the conditions 
that force its application, with very complete illustrations of the plan as 
variously applied. There is also considerable detail regarding the correlation 



I02 America)! Forest Rci^ulation 

of age with diameter, and yield table volumes with stand estimates, in order 
to predict growth and correlate growth with our irregular and perplexing 
extensive stands. This mass of data teaches the student to think regulation 
in terms of cutting cycles, age classes, per acre growth in board feet and a 
future sustained yield ; it is a correlation of gr^owth and regulation in extensive 
stands. But where age classes can be ditferentiated in the forest at a reason- 
able cost and cutting cycles largely reduced from the extremes of J^ r or ^ r, 
then the "American method" does not appear necessary. Furthermore, 
during the first cutting cycle it may be necessary to sacrifice something 
in future regularity of cut in order to save overmature timber that will other- 
wise be lost through decay, windfall, and other natural accidents to the veteran 
stand? Judging from § 154, Part II, this loss would amount to at least one- 
fourth the stand if ripe western yellow pine trees are held 100 years beyond the 
rotation age. As a matter of fact, the actual loss, though often exaggerated, 
is sometimes also far greater, because the soil covered by the veteran stands is 
not only actually losing timber, but is occupying space that ought to be pro- 
ducing a rapidly growing young stand. Moreover the longer overmature 
stands are held, the more difficult will be regeneration, which with high labor 
costs and extensive areas in the West, must be secured largely by na<tural 
regeneration. Therefore deliberately planned cutting cycles of fifty to a 
hundred years are economically unsound, when not absolutely forced by local 
conditions. 

For example in § 176 the cut for a second cutting cycle is worked out for 
lodgepole pine. There is no objection to this merely as a trial balance but 
of course it must be recognized that in the second cycle (1940-1980) there 
will be clear cutting, intensive thinnings and probably the use of the allot- 
ment or stand method of regulating the cut. 

Professor Chapman has given an illustration from the Coconino Forest 
(Arizona) considered as a whole. Ultimately there will probably be evolved 
two classes of local conditions, namely, (a) intensive and (b) extensive. If 
this prediction is accepted as likely, then the two classes of conditions might 
have been recognized today by varying the length of tHe cutting cycle in 
different portions of the forest. At least this can be done within the next 20 
years. To presume that a cutting cycle of a hundred years will continue, even 
in the West, seems absolutely improbable. There is another important point 
in policy to be considered in weighing a method. How much accuracy 
is justified in extensive conditions? To my mind a rather crude method that 
will give rule of thumb results is sufficiently accurate if the more accurate 
calculation means an appreciably greater initial expense. Take a case in 
point — the amount to cut on the Coconino Forest (par. 166). According to 
Chapman, the French method of 1883 indicated 28 million feet as the annual 
cut. Von Mantel's crude formula 315^ million, the Austrian 38J/2 million and 
the American method 27, the last figure being assumed by Chapman as the 
correct cut. The mean annual growth was computed to be 42^ million. 
Who would say that the French method is not sufficiently accurate in this 
particular case? And cannot the forest be split up intcD a number of 
working circles? And should not the cutting cvcle of 100 vears be reduced to 



Area and Arca-Voluuic Methods 103 

50 ±: ? Furthermore, if we allow the regulator to guess at the future, it is 
certain that with fire protection, protection from destructive sheep grazing, 
thinnings, some planting or sowing, and with better methods of silviculture, 
Vie shall probably reduce our 200-year rotation to from 140 to 160 years. 
Moreover, today we know for a fact that much of the growing stock is in 
overmature stands. Why not cut 35 to 40 million and get rid of the mature 
timber faster? Can the Forest Service justify the smaller cut of 27 
million? This is extremely doubtful. This discussion, which admittedly 
is open to argument, merely tends to show the student the danger of placing 
too much emphasis on regulating the cut by mathematics, as opposed to the 
demands of silviculture and policy. The administrator must base the final 
decision on a compromise between regulation mathematics, silviculture, and 
basic policy. Whatever the answer, it is at least difficult to justify holding 
saleable overmature timber longer than necessary. Just now should not 
sound silviculture come first? Even in Europe the tendency is towards silvi- 
culture rather than towards rigid regulation. 

The great similarity between Chapman's former "American method," as 
described by Recknagel, and the French method of 1883 is evident. In 1917 it 
was really an allotment of diameter classes to irregular periods (gauged by 
the years allotted to each age class) instead of a straight volume-area allot- 
ment. But the method has been considerably modified from time to time. In 

1917 Recknagel said regarding it that it was " an adaptation of 

Hartig's volume-period method but greatly simplified." Today it 

emphasizes cutting cycles and felling reserves. By demonstrating the ease of 
correlating diameter, age, and growth in irregular stands Professor Chapman 
has rendered a great service. For the details of the American method the 
student is referred to Part II, which follows, and which contains an immense 
amount of valuable and sound mensuration, besides a philosophical discussion 
of the application of regulation to extensive American stands. 

In studying the methods described in Part II it is important to visualize 
the probable future development of permanent transportation in the South 
and West. It is confidently predicted that permanent transportation must 
be secured within the next half century, for without it forest management 
will prove a partial failure. The building of temporary logging railroads and 
the deliberate plan of cutting cycles 50 to 100 years in length will surely 
result in the failure of forest regulation, because permanent transportation is 
the foundation on which our future continuous forest production and stable 
local forest industries must rest. Moreover it must be admitted that the 
basic regulation plans of Part II may be gradually replaced by the allotment 
or stand method when a clear cutting system becomes more general with 
intolerant species, as it must eventually. But it must be recognized that 
regulated clear cutting means a delay in harvesting the stands in the last 
period.* 

* For all clear cutting silvicultural systems an allotment, simple area, or stand method 
should usual!}' be employed. For selection fellings the French method of 1883. or a 
modification of it, or the new "American Method," may be used if formulae methods are 



I04 American Forest Regulation 

105. Quiz. Why is volume alone an unsatisfactory basis for regulation? 

1.S area alone satisfactory? 

Explain regulation by fixed areas? 

When should it be used? 

How does area allotment differ from regulation of cut by fixed areas? 

Explain area allotment. 

Why is an area-volume basis of regulation more satisfactory than volume allotment? 

Explain deficiencies of volume allotment. 

Cite the more important principles of allotment methods as applied in Germany. 

Give disadvantages and advantages or area-volume allotment. 

Define stand selection; what is its basis? 

Why is the stand method a good scheme of regulating the cut? 

Illustrate conditions which would fully justify its application. 

What is the essential difference between area-volume allotment and the stand method? 

What is the basis for the "American method" of regulating the cut? 

What are its weaknesses? Its strong points? 

Is it a permanent or temporary method of regulating the cut? Why? 

(See Part II for further and detailed quiz questions.) 



considered undesirable, but see also Part II for methods which are recommended by 
Chapman. The frank discussion of the "American method" will not be misunderstood 
by those who have read H. G. Wells' recent "Outlines of History." (See § loi.) 

When checking over my references to his own writings Professor Roth made many 
valuable suggestions. Every student of regulation should read Roth's article in the 
October, 1921, Forest Leaves. 



PART II 

CORRELATION OF REGULATION AND GROWTH 
IN EXTENSIVE AMERICAN FORESTS 

BY 

H. H. CHAPMAN 

Haniman Professor of Forest Management, Yale University. 



CHAPTER X 

THE CUTTING CYCLE AS A DETERMINING INFLUENCE 
IN AMERICAN FOREST REGULATION 

io6. Attitude of Private Owners. Forest Regulation in America with the 
object of securing a sustained yield is as yet but little understood by private 
owners. The idea itself marks such a departure from accepted standards of 
forest practice, and entails so many apparent risks and sacrifices of immediate 
profit, that it is usually rejected in favor of a more rapid realization of value 
from cutting mature timber. The private investor understands stumpage 
values. He does not yet grasp forest values, and seeks to convert stumpage 
into forms of property and investments with which he is familiar. 

107, Preliminary Requirements. Before regulation of cut to secure sus- 
tained yield is possible on forest properties in this country, several preliminary 
developments are necessary. First comes the acquisition, establishment and 
improvement of a forest estate of sufficient size to justify management as a 
separate financial venture rather than as a side issue to some other source 
of income such as farming. 

The permanence of ownership, which in this country is sadly lacking, and 
also of policy, which here means a more complete acceptance of the economic 
and technical basis of forest production, is next in importance. As yet, 
areas of sufficient size when managed for timber are usually not intended as 
permanent holdings. This is the case with the vast bulk of lumbermen's 
lands, and often those which might constitute true forest estates are chiefly 
of interest to the owners as parks or for game and fish preserves. 

The improvement of markets and of accessibility by better transportation 
comes next. On tracts where in the past but a small percentage of the 
standing timber by species or sizes could be marketed, no permanent plan for 



io6 American Forest Rc^s^idatian i 

sustained yield was possible. The final de\cloi)ment of stumpage values for 
the main body of the timber will alone permit of the intelligent consideration 
of regulation of the forest. 

io8. Obstacles to Regulation of Yield. One of the greatest obstacles to 
regulation of yield is the character of the forests themselves ; the fact that 
so far the cut has been largely from virgin forests often of mixed species, 
instead of from second growth produced artificially or grown as even-aged 
stands free from suppression. The dif^culties are: 

First, a surplus of overmature, usually decadent timber which not only 
requires rapid removal leading to and establishing the custom of overcutting, 
but is accompanied frequently by a deficiency in younger age classes, hence 
tends under any method of regulation to perpetuate an abnormal condition 
leading to a reduction of the cut l)elow the normal sustained output at the 
expiration of the first cutting cycle. 

Second, the extensive character of investment and of operation indicated in 
order to remove this surplus of large stock economically and profitably, 
render the largest possible area accessible by reducing logging costs, and 
realize the greatest stumpage value. The rate of annual cut so established, 
and the rate of depreciation on the investments required usually tend to 
exhaust the growing stock completely in a period far too short to secure a 
continuous sustained yield. This does not preclude forest management, for 
it is possible to secure on such cutover areas a renew^al of forest growth by 
natural or artificial reproduction. It does substitute periodic or intermittent 
yields for regular annual or sustained yields. Where transportation will 
continue to be expensive, a permanent policy of periodic rather than annual 
yields may be necessary, with intervening periods during which practically 
no revenue is realized from timber cutting. 

Third, the absence of data on the rate of growth of the forest prevents 
the determination of the proper annual cut by which sustained yield might 
be secured. The problem is to prolong the first cut on virgin forests until a 
second cut can be made on areas previously cut over. To determine the 
length of this period, the rate of growth of timber left on cutover lands and 
of reproduction, is required — while to determine the amount which should 
be cut annually during this period, the rate of growth of the timber now 
standing is needed. There are considerable difficulties in the way of deter- 
mining both problems, and until this data becomes more reliable, the regulation 
of the cut on virgin forests will be equally unreliable. 

Effect of over-cutting. On forest areas which have already passed through 
this first cutting cycle, especially where the processes of cutting have been 
those of forest denudation, the problem of regulation of the cut is indefinitely 
postponed until the establishment or re-creation of a growing stock which 
may be regulated. Silviculture, not regulation, is the important consideration 
on such depleted forests. 

Regulation of yield in this country can be applied at this time only on 
forests which have not already been cut over, or on which a second growth is 
approaching maturity, hence the problem first in importance is one of pro- 
viding a gradual transition of a virgin forest to one capable of permanent sus- 



Cutting Cycle in Regulation 107 

tained yield, in place of the process of overcutting which involves a subse- 
quent slow and discourac^ing period of restoration of forest capital. 

109. Policy as Influenced by Character of Ownership, Ozvners who can 
Afford Sustained Yield. Under present conditions in America the classes of 
owners who can best afford to prolong the cut of virgin timber so as to com- 
pletely bridge the gap between first and second cuttings are public owners and 
private owners whose principal investments are in some form of manufactur- 
ing dependent on wood, and who desire to own and control a sufficient supply 
to insure the perpetuation of their business. Public forests stocked with 
mature timber and managed for commercial production lie chiefly in national 
ownership, and should always be managed for sustained yield unless it can be 
positively shown that such management would prevent the proper exploitation 
of the timber and permit it to go to waste unused. 

Policy for Other Private Ozvners. But with private owners, other than the 
class mentioned, the course apparently indicated is, first, a considerable reduc- 
tion of the investment in overmature, merchantable forest capital, second, the 
reservation of young thrifty timber and the reproduction of the forest by 
sound silviculture and protection, third, the final restoration of the forest 
capital by growth. 

It is impractical for such typical forest owners as the majority of lumber- 
men to curtail the rate of cutting to a point which will permit of sustained 
yield during such period of transition. The one item of taxes on mature tim- 
ber tends to prevent this, even without the additional costs due to losses in 
timber and interest charges. But this economic justification of overcutting 
makes it doubly difficult to check the process of denudation in time to secure 
reproduction, and ultimate restoration of the forest capital. With the exhaus- 
tion of the growing stock, the owner's interest is gone. He has never grasped 
the idea of forestry as a sustained business of timber growing. For practi- 
cally all private forest owners whose interest in forests as productive property 
is not based on larger outside investments, sound management demands not 
the complete removal of the merchantable capital, but rather the determina- 
tion of the largest per cent of young timber zuhich it is possible for them to leave 
for a second cut. By this mearfs the value tied up in the investment can be 
reduced, yet its future productiveness preserved, and not only will the repro- 
duction of the forest be made more certain but the period which must elapse 
before a second cut can be made will be greatly lessened. 

In this form which tends to future, though intermittent yield, the regulation 
of yield is already being practiced by many private forest owners, and should 
be universally and immediately adopted by the remainder. On denuded 
forest lands, regulation will be postponed until the growing stock is built up 
to a point where there is something to regulate. 

Goal of Private Ozvners. *i.t is evident that in this transition of a virgin forest 
to a regulated forest, the process, both as to speed and thoroughness of execu- 
tion is not an end in itself, but a means of making the property more useful and 
profitable, and of accomplishing to a greater degree the purposes for which the 
business involved in its management is conducted. It is a basic premise that 
true forest land cannot be as profitably used for any other purpose as for tim- 



io8 American forest Regulation 

ber production and often has no other use whatever. On this basis its perma- 
nent denudation is not profitable to tlie future owners, whoever they may be, 
whether public or private. Hence, clear cutting can profit the present owner 
only in the sense that he is a wrecker of a going concern and intends to 
sacrifice the permanent assets, that is, to abandon the land, or sell it, and 
junk the enterprise. 

If the present owner once recognizes this responsibility or trusteeship for 
land capable of growing crops of timber, his entire attitude towards the 
management of forest land must necessarily change. This does not involve 
an immediate attempt to secure present sustained yield or complete transition 
to a regulated forest, but it will mean the careful appraisal of the possibilities 
of forest management for production of timber by growth, its costs, the 
relative profital)lcness of logging small versus large timber, and the measures 
required to secure, at some future time, a second cut of timber, and finally 
the extent to which the period which must elapse between cuts can be 
shortened by curtailing the present operation. In all of this, the ruling 
consideration must be financial, a question of returns on the investment. 
But there must be no deliberate intention to destroy the possibility of forest 
renewal. 

no. Goal of Public Management. But with public and especially with 
national forests, no such limitations exist to prevent the immediate adoption 
of the principle of complete transition to a regulated forest by proper cutting 
of the original growth. The public purposes of management are primarily 
public benefits through the yield of forest products, not through profits from 
sale of timber. With lower interest rates and the emphasis shifted from 
the side of income to that of production and supply, national and other public 
forests must be managed to obtain sustained yield, and the annual cut must 
be regulated before it threatens to exceed the capacity of the forest or the 
requirements of the transition period. 

III. Influences Determining Initial Cut per Acre. In the practical 
application of regulation either to virgin forests or to restocked areas, the 
owner is at once called on to determine the character and severity of the 
first cutting to be permitted. Even on public forests, logging cannot be 
conducted at a loss. In such case it should not be conducted at all, either 
by purchasers of stum page or at public expense. Timber which must be 
logged at a loss is in efifect inaccessible until economic conditions change. 

In direc1> proportion as the cut per acre and consequent total cut on a 
logging unit is increased, the logging costs per unit of product are reduced, 
the accessible area thereby extended, and the marginal value of stumpage 
enlarged. But at the same time the stock remaining after cutting is reduced, 
the period required to produce a second cut is lengthened, the risks from 
slash and insects increased and the difficulties of obtaining sustained yield 
multiplied. 

Whatever tends to increase logging costs and thus reduce the margin 
between such costs and sale value of the logs or lumber tends to require a 
heavier first cut per acre. Transportation has the greatest effect on logging 
costs. Permanent road systems have seldom been provided as yet. Tem- 



Cutting Cycle in Regulation 109 

porary means of transportation is the rule, and the entire cost of such 
expenditures is borne by the stumpage logged in the first cutting. 

Where these conditions demand so severe a cutting that the possibility 
of natural reproduction would be destroyed, private owners are accustomed 
to proceed with this forest destruction. Where such conditions are true on 
a public forest, the timber should be reserved for an increase in marginal 
profits and not cut until it can be logged in a manner which will safeguard 
the future stand. 

From the standpoint of the best silvicultural treatment of the forest, it 
frequently happens that natural reproduction is most easily obtained and 
thrives best when a fairly heavy cut is made, and that too conservative a 
cutting per acre leaves the forest still in a stagnant condition, retards renewal, 
or unfavorably afifects its composition. In other. cases a more conservative 
cut is indicated. If forest management is to be practiced at all, the cut per 
acre cannot exceed the minimum which will leave the forest in condition to 
perpetuate itself by reseeding unless it is definitely determined that artificial 
planting following clean cutting is the most desirable practice. 

These two practical considerations, lumbering, and silviculture, come first 
in determining the exact nature of the problem of regulation confronting any 
class of owner. Together, they determine the per cent of the stand to be taken 
in the first cutting. Neglect of the need for regulation would induce the 
operator to take too heavy a toll of the forest, while, on the other hand, over- 
emphasis of sustained yield, to the neglect of the actual practical conditions 
affecting both the utilization and reproduction of the forest, might erroneously 
indicate a cut far too light for sound management. 

112. The Cutting Cycle. Definition. Length. By definition, the cutting 
cycle is, first, the period elapsing between two successive cuts on the same 
cutting area or logging unit, and second, the period which is required for 
logging operations to go once over the entire working group. 

In order to obtain a sustained yield, these two definitions must both hold 
good, for if the period required for cutting operations to go once over the entire 
area is shorter than the number of years which must elapse between successive 
cuts on the same area, intermittent yields with intervening periods of sus- 
pended cutting will result. 

In order to return for a second cut on an area, there must be some timber 
to return for. While the first cut, which may remove a large surplus of over- 
mature timber, will normally exceed the second, yet the second cut must 
yield a sufficient quantity per acre to pay the cost of going after it, just as 
in the first operation. 

The length of a cutting cycle based on a plan for continuous cutting or sus- 
tained yield will therefore depend first on the per cent of the original stand 
which is removed; second, on the character and age of the stand left on the 
area ; third, on the rate of growth, after cutting, on this residual stand and on 
the immature timber and reproduction. Upon these factors depends the 
volume of the future crop and the period required to produce it. 

113. Growth on Cutover Lands, To determine this period thus requires 
a knowledge of the growth which will be secured on cutover lands on the basis 



no American Forest Regitlation 

of area. Otherwise, the determination of the period before a return is possible 
is but a guess. The first effort in American regulation for sustained yield 
must therefore be directed to obtaining the l)asis for growth predictions on 
the trees left on cutover lands and on stands of immature timber. Merely 
to decide upon a given period for cutting the present volume in the forest 
gets us nowhere, unless we know just why the said period is chosen and 
what will happen when it is ended. The logger usually knows about how 
long a cut he has. But the span of life of the logger's operations has no 
relation to the next cut. Regulation is an attempt to prolong logging until the 
second cut is ready and knowledge of growth is the key to this problem 
whose solution must precede intelligent regulation. 

114. Growth on Virgin Forests. Intermittent Yields. The second need 
is to determine directly how much can be cut annually from the unit, in 
order to round out or prolong the cutting to the year of beginning the second 
cut. If it is found that the indicated cut per year is too small to permit of 
economical and efficient logging, then sustained yield will probably give place 
to intermittent yields. But to determine the true permissible annual cut, 
the change in volume of the stand by growth or decadence during this period 
must be approximately known, else the cut is more or less approximate. 
This requires a separate study of growth in the virgin forest. This data is 
less important than the study of growth on cutover lands which determines 
the length of the cycle, — it merely aids in carrying out the intention to com- 
plete the cut in this given period, without having it either fall short or 
overlap. 

The solution of this double problem of growth may be sought either on 
the basis of accurate and painstaking investigations, or in their absence, 
upon such approximate evidence as can be obtained pending more definite 
determination. The point to be emphasized here is that without the double 
decision, first on the length of the initial cutting cycle, second on the limitation 
of the annual cut during this cycle, there can be no effectual progress in 
regulation of yield, but only general assumptions based on crude suppositions 
such as that expressed by Von Mantel's formula. (See paragraph 82.) 

115. Relation between the Cut per Acre and the Cutting Cycle. The 
determination of the rotation is itself the result of growth study. Without 
the rotation, not even these rough and ready methods of approximation 
such as Von Mantel's, are possible. But the cutting cycle takes into imme- 
diate account the actual condition of the entire area, with especial reference to 
the distribution of existing age classes and the proportionate area stocked 
with young timber. This the rotation alone does not do. 

A short cutting cycle means a relatively small cut on each acre which is cut 
over in a given logging operation, and the corresponding spreading of the log- 
ging over a proportionately larger area in each year to cut the same quantity 
annually. Permanent road systems coupled with intensive demand permit 
of cutting cycles even as short as six to eight years. Conversely, a heavy 
cut per acre and concentration of the annual cut on a small area demands 
a lengthening of the cutting cycle in the same ratio. American forest regu- 
lation since it is primarily concerned for the immediate present with the 



Cutting Cycle in Rci^ulation in 

remaining stands of virgin timber, which are comparatively inaccessible, will 
be based largely on a heavy cut per acre and a correspondingly long rather 
than a short cutting cycle. Conditions similar to most well managed, arti- 
ficially grown and accessible European forests, with short cutting cycles, will 
govern the regulation of the more accessible second growth forest areas in 
the East and elsewhere, and should similar conditions become established 
in regions now relatively inaccessible, the cutting cycle can and will be short- 
ened to coincide with these altered conditions. 

The creation or adoption of a relatively long cutting cycle as a basis of 
regulation of these virgin forests is the only measure which permits of the 
orderly working out of practical regulation under the conditions of transition 
cuttings where it is now most urgently needed. But a cutting cycle equalling 
from 54 to 3^ of the rotation will affect all the other elements entering into 
the problem of regulating the cut. These elements are, 
The area to be cut during the cycle, 
The felling reserve. 
The minimum exploitable age, 

The growth available for cutting during the cycle, 
The volume of the total cut and of the annual cut, 
The "normal" growing stock. 
These relations have apparently been overlooked in previous discussions 
of regulation of American transition forests but their comprehension must 
precede the formulation of any practical plan of regulation involving a long 
initial or transition-cutting cycle. 

ii6. Similarity of Even-aged and Many-aged Forests. In order to make 
clear the influence of the cutting cycle upon these several factors, we must 
first harmonize the conception of a forest composed of even-aged, and one 
of many-aged stands, termed frequently a selection forest. In theory, a forest 
of even-aged stands may contain but a single series of age classes each com- 
posed of a single even-aged stand. But in practice, especially in forests where 
the best silvicultural management has been applied, such a forest would be 
composed of many different series of age classes and of a much larger number 
of relatively smaller areas occupied by stands of even age. These separate 
stands are intermingled but still exist as distinct areas. But in cutting, the 
operations will be spread in any year over a much wider general area to 
reach these patches than would be the case with a single series of age 
classes; and within a single cutting cycle, logging operations would reach 
into and cut only the mature stands in each -block or logging unit in the 
forest in succession. 

It is but one step further to carry the process of intermingling to areas 
of less than an acre, or to the single tree or small group. The number of 
age classes, their volume, and the total area occupied by each age class can be 
the same, — the form and management only is different. 

The two forms of forest are not identical from a silvicultural standpoint 
since the laws of tree growth dift"er specifically, but from the standpoint 
of regulation and of the cutting cycle they may be considered as essentially 
the same. 



112 American Forest Regulation 

117. Residual Growing Stock and Felling Reserve. Under the definition 
of a cutting cycle, no cutting (except thinnings) is done on an area between 
two successive major logging jobs or fellings which are separated by the 
period representing this cycle. 

After each cutting, a residual stand is left on the logging unit, composed 
in forests of even-aged stands of all the stands below the felling age, and in 
forests of many-aged stands, of all stands below the felling size, i.e., too 
small to cut under the limitations agreed upon as to size or age. This may 
be termed the residual growing stock (not to be confused with the term "normal 
growing stock" as commonly used to indicate a theoretical total growing 
stock required in a normal forest. Chapter VI.) 

During the cutting cycle, the stands and trees constituting this young 
stock are growing, and a certain proportion of the older stands in the even- 
aged form, and of the older trees in the many-aged form, grow into the age 
and size classes suitable for cutting, after the area has been cut over, and 
replace the timber cut. This portion of the growing stock is termed the 
felling re.'serve. 

118. Illustration of a Transition Cutting Cycle in a Normal Forest. The influence 
of the cutting cycle upon the forest can best be brought out by an illustration. Let us 
assume that we have a forest of all ages ranging from one to iifty years, and that each 
of these age classes is scattered over the entire area of the forest and not grouped, so 
that in order to harvest each crop when it reaches fifty years of age, the entire area 
would have to be gone over every year. But it is desired to concentrate operations on 
one-tenth of the area annually, with a cutting cycle of ten years, or 1/5 r. 

Let cc = cutting cycle of 10 years and r = rotation of 50 years. 
The area of the forest can be assumed as 500 acres, divided into 10 blocks or logging 
units of 50 acres each. The amount of ripe timber to be harvested annually will 
occupy 10 acres all told. 

To fulfil these conditions, this forest may have 500 separate even-aged stands of one 
acre each, ten of which fall in each age class, or, if it is of a typical many-aged form, 
every acre will have trees of all of the 50 age classes present, but the aggregate area 
of each age class on the forejt will be just 10 acres. 

If regularly distributed, the even-aged form will have on each of the 10 fifty acre 
blocks or annual cutting areas forming the 10 year cutting cycle, but i acre fully ripe,— 
while on the many-aged forest trees fully ripe are found on each of the 50 acres in 
the block, but their total volume is equivalent to but one acre of ripe timber in each 
block. To cut each stand or tree when ripe, in such a forest, would require cutting 
within every block, in every year, or a cutting cycle of i year. 

Effect of Transition Cuttings on Forest. By contrast, in the first year of a ten-year 
cutting cycle the annual cut must be concentrated on one block of one-tenth of the 
total area or 50 acres and it must cover 10 acres instead of but i acre, in this block, 
and neglect the ripe timber in the other nine blocks for the present. To secure this 
amount of timber, the first year's cut must include besides the one acre of ripe timber 
on this area, 9 acres more — and to do this we must cut timber down to 41 years in 
age. The age of the youngest timber cut would thus include stands down to the 
limit of r — cc or 40 years. 

But at the end of the second year, when cutting in the second block of 50 acres, it is 
not necessary to cut 41 year old timber. Each of the 10 acres to be cut is one year 
older, ranging from 42 to 51 years. Should the cut be made to include all timber on 
the block down to the same age or the same minimum size limit as in the first year, 
i.e., r — cc years, ir acres would be ready for cutting aged 41 to 52 years. This com- 
parison can be traced through the 10 year cutting cycle. In the first case, where but 



Cutting Cycle in Regulation 113 

10 acres are cut annually, the average age of the stands cut increases until at the end 
of the loth year the cut is from 51 to 60 year old timber; 100 acres have been cut 
over. The average age of the timber cut during the 10 years was, for the first year, 
45 years, for the last year 55 years, and for the cycle 50, or r, years. This process can 
be repeated in five successive cycles until the entire forest of 500 acres is cut. 

The effect of this cutting cycle on the form of the forest nov\^ becomes evident. If 
reproduction is by planting or occurs immediately, the forest in the fifty-first year will 
be composed of fifty instead of five hundred crops, each ten acres instead of one acre 
in size. On each block there are but five age classes, one for each lo-year cutting 
cycle. In this rotation the average period of growth, ^ cc or 5 years marks the 
extreme variation in average age of annual cuttings from r or fifty years, but the 
average of all cuttings is fifty years in the second rotation, each stand matures at 
exactly fifty years, each is 10 acres in size and each can therefore be cut when ripe, 
although the cutting is now made on a ten-year cutting cycle. 

Establishment of Minhimm Exploitable Age. Thus the felling reserve originally con- 
tained al! stands from 41 to 50 years old inclusive, but in the tenth year contains stands 
up to 60 years old, or stands from r — cc to r + cc years respectively. The cutting 
limit must evidently permit the removal of timber below r years in age in order to 
effect the transformation from a many-aged to a regulated forest. The age r — cc or 
40 years is the minimum exploitable age, in this illustration, and is evidently afifected by 
the length of the cutting cycle — the longer the cycle, the greater the inroads upon the 
stock not yet fully matured to the age of r years. 

Relation hetiveen Rotation and Cutting Cycle. It is evident that as soon as 
the transition of form and arrangement of age classes is completed, the timber 
can all be cut at the age r years which is the maximum age of the residual 
growing stock, plus the period of the cutting cycle, and equals the rotation. 

In this case, a transition of one perfectly normal forest to another is chosen 
as an illustration, in which there was originally no overmature stock, and 
the only change made was a regrouping of age classes made necessary by the 
adoption of a 10 year instead of a i year cutting cycle. 

The same principles apply to the transition of a virgin forest composed of 
timber of all ages, whether scattered as single trees, grouped in small patches, 
or assembled in larger areas. The rotation r will mark the average age at 
which the stands should be cut — but unless the minimum exploitable age 
is set lower than this the timber even in the second cutting cycle will reach 
an average age greater than r years before it can he cut. The cutting creates, 
from this original forest, a forest moulded after the plan on which this cutting 
is regulated. 

This felling reserve is simply the upper portion of the growing stock. 
In a regulated forest none of it finally need be allowed to exceed the age of 
the rotation, although it did and must exceed it in part during the period 
of transition cuttings. The final result is, that the cutting cycle is merely the 
last period of the rotation r, while timber both below and above r in age and size 
has been cut. 

119. Ultimate Form of the Forest. The first ultimate effect of the cutting 
cycle, granting that reproduction is secured promptly, is then to modify the 
arrangement of age classes as to area and number to conform to the routine 
system of cutting of which the cycle is an application. There will be, ulti- 
mately, as many age classes on each area or logging unit as there are cutting 
cycles in a rotation. If the cycle is ^ r, the many-aged character of a stand 



114 America)! forest Regulation 

will tend to give place to two main age classes, — if ^ r, to three classes. The 
second ultimate effect, contingent on the first, is to produce crops which will 
reach just the merchantable age desired, or r years, on successive areas of 
proper size, annually. A short cycle, adapted to the perpetuation of a many- 
aged form of stand, permits numerous separate crops to originate on the same 
area unit during the rotation. Under the moulding force of a consistent 
policy of regulation the plastic forest tends to assume the form which most 
nearly fulfills the desired c)l:»jectives. 

120. Principle of Allotment of Definite Stands for Cutting During Period. 
But the liiiiiicdiate effect of the cutting cycle, for the first rotation, will depend 
upon the method of its application. 

In the illustration given, the principle of regulation employed is that of 
allotment of definite stands occupying a definite total area, for cutting during 
a given period. The cut for the period is the initial volume of these stands 
plus the growth for ^ cc years. The fact that during the period younger 
stands will mature to a minimum exploitable age over the whole area is 
ignored, although approximately half of this maturing volume will be upon 
areas not yet reached in cutting, and this accretion of exploitable volume on 
such areas is wholly apart and in addition to the growth on the areas and 
stands allotted for cutting during the period. 

If, in theory, none of these maturing" stands are to be cut till the second 
period, then the cut is in effect as described by the first illustration, and the 
forest at the end of the first cutting cycle in theory has no regular established 
felling series for the next cutting cycle, but is again covered by an equal 
number of stands of all ages in each cutting" area. Only the reproduction for 
this period has been "regulated" to conform to the new cutting cycle, and this 
will not be cut until the next rotation. 

But in practice this is not the way it is done. The calculation of volume to 
be cut is a quantity check, leaving the areas or specific stands to be selected by 
the forester. He will take the oldest or those most in need of cuttting. Allot- 
ment of specific stands long in advance of operations has lost favor in European 
practice where the eft'ects of a cutting cycle are reduced to a minimum by 
shortening the cycle and going twice or three times over the area in an allotted 
period, e.g., for a period of 20 years, the cycle may be but 5 years in length and 
each area is cut 4 times within the period. Or the periodic allotment of areas 
is made moveable or progressive by the continuous addition of areas as others 
are cut over. (French quartier bleu method.)* 

With short five to eight year cycles the dift'erence in age between stands 
cut at r years, or at r — cc or r -|- cc years docs not exceed the limits expected 
in the ordinary management of a regulated forest. 

121. Principle of a Horizontal Cut to Fixed Limits of Age or Size. A 
felliiii^ rescrz'c. or serial arrangement of the merchantal)le age classes, is actu- 
ally created by cutting a forest once over during a cutting cycle, whether or not 
it is recognized in the plan of management. 

But when as in the transition rotation for virgin forests, the rotation may 
l)e fairly long to begin with, and the cutting cycle, being y^ or y2 r, may 



See page 239, Studies in French Forestry, John Wiley & Sons, New York. 



Cutting Cycle in Regulation 115 

be between 40 and 100 years in length, the method of theoretical allotment 
of given stands or age classes for removal during such a long cycle will 
differ so widely from the practical demands of regulation and of logging, 
that these discrepancies can no longer be concealed or ignored. The progress 
of the stands by growth and decadence goes on. In the logging of successive 
stands, by the theory of aUotnients only the timber which had reached the 
age or size agreed upon at the beginning of the period would be logged 
within the period and this would mean, as in the illustration given, a con- 
stantly increasing age or diameter, but this time over a long period. 

Instead, the cut will be forced to proceed along a horizontal line of cleavage, 
removing from each successive area not merely the, stands which originally 
were ready for cutting, but also those which have matured since and are ready 
for cutting when the area is to be cut over. By this method, a felling reserve 
grows up on the areas behind the saws, i.e., is created in the first cutting 
cycle instead of at the end of the first rotation, for the reason that on areas 
ahead of the saws all the newly maturing crops are cut along with the 
original stands. It is self-evident that if logging and silvicultural conditions 
originally demand the removal of a given per cent of the stand, they will 
continue to do so as long as the basic economic factors remain unchanged, 
and after that the working plan itself must be revised. 

Application of this Principle to Transition Cuttings. This working principle 
may be termed the principle of a horizontal cut and felling reserve as contrasted 
with that of specific allotment of stands. Taking the forest described in the 
former illustration, but applying this principle of cutting instead, the forest 
will be cut over by removing each year all the stands on each cutting area 
which are ready to cut, i.e., are forty (r — cc) years old, in order to create at 
once a cutting series equivalent to a ten (cc) year cutting cycle. 

Effect on Area and Volume to be Cut Annually. As one additional crop reaches the 
minimum exploitable age each year in each block, the cut at the end of the first year 
under this plan in the previously regulated or normal many-aged forest would cover 
eleven acres and for the twentieth year, twenty acres, while during the ten-year cycle, 
instead of 100 acres being cut, the area logged will be 150 acres. This method not 
only increases the area cut in the first period by fifty per cent but increases the volume 
by a somewhat smaller per cent. (The young maturing stands have ten years less 
growth than those originally in this period, hence a smaller volume.) The process 
would remove all of any surplus stock during the first cutting cycle. This surplus 
consists of the stands which must grow to a maximum age of r-fcc years (60 years), 
before being reached in logging, the actual ages of these overmature stands falling 
between r and r -}- cc years (51 to 60 years). The efifect of the horizontal cut would 
be to reduce the growing stock below normal, and prevent any stand in the future 
from growing to an age exceeding r years, as long as the plan is adhered to. 

During this first cutting cycle, the advancing age of the surplus would raise the 
average age of the stands cut, from 45(r — ^cc) to a final 50 (r) years in the last 
or tenth year of the cycle. 

For each cutting cycle after the surplus is removed, during the first rotation, the 
average age of the stands cut will be r — ^cc or 45 years, after which the normal 
arrangement being secured, the stands during the second rotation may be cut at r or 
50 years. 

122. Application of These Two Principles in Contracts for Purchase of Timber 
Cutting Rights. The distinction between these two methods of regulation may be 



ii6 American Forest Regulation 

further illustrated by citing certain timber sale contracts for the purchase of standing 
timber for cutting. In these contracts a diameter limit is usually specified, and a 
period fixed within which all timber so purchased must be removed. Numerous law- 
suits have resulted from failure to recognize the fact that trees grow in size. The 
owner who sells would favor the allotment method of cutting described above, by 
which none but the trees which were of the stipulated size of age classes at the time 
of sale could be cut within the period. This would coincide with the first illustration — 
the purchaser would get the growth on the allotted stands but no new or maturing 
stands. 

The purchaser, however, insists that he is entitled to a horizontal cut of all timber 
which is of the specified diameter at the time he reaches the area in question, claiming 
that it is utterly impractical to distinguish from year to year, in cutting, the trees which 
were below the given sizae in the first year of the cycle and that nothing was said 
about this anyway in the contract. If^permitted, he therefore cuts on the plan described 
in the second illustration leaving only the timber which matures behind the saws or 
the so-called felling reserve. If the contract is so loosely drawn as to permit him to 
cut the same area over more than once, i.e., cut in two cutting cycles, he can of course 
begin where he left oflf and cut the felling reserve, continuing this process indefinitely 
as long as his contract permits him to cut. The Carr contract for the sale of timber 
on the former Vanderhilt holdings, now the Pisgah National Forest was let on this 
basis, and has resulted in great embarrassment to the government. It would be just 
as well for owners of timber to recognize sooner or later that trees grow in spite of 
their indifference to forestry. The basis of a straight or horizontal cut is the onlj^ 
practical basis of a contract for cutting, but the payment should not be in a lump sum 
at time of sale, — rather, on the basis of scaled cut and with provisions for advance 
in rates on a long period, with confinement of the cut to one cutting cycle, or once 
over the area. 

123. Effect of a Surplus of Overmature Timber upon the Minimum Exploitable Age. 
While in large areas the original growth may resemble the normal forest of our 
illustration in having no regularly arranged felling reserve but rather, a distribution of 
all age classes over the entire area, yet their chief characteristic is an excessive surplus 
of growing stock when measured by empirical njormality (§65). When, even on this 
empirical basis, the forest, because of past fires and abuse has less than the normal 
quantity of overmature and ripe timber, yet it is sure to have stands whose age greatly 
exceeds that of any reasonable rotation for future management. 

This surplus, or in its absence, the excess in age of the mature stands, makes it 
unnecessary in regulation to draw on stands as young as r — cc years to make up the 
cut for the first cycle. If on account of good transportation the cycle can be shortened 
and the annual cut distributed correspondingly on a larger gross area, the cut for the 
first or even the first two cycles, depending on length of cycle and ccxndition and 
quantity of overmature stands, may be confined entirely to trees which are older than 
r years. This postpones the reduction of the surplus over a corresponding period. 

But with a long cutting cycle, the lack of properly arranged cutting series in the 
forest and the necessity of a heavy cut per acre will compel the cutting of trees less 
than r years old in the first cycle, until this series is established. It will twt be neces- 
sary to cut trees r — cc years of age, however, l)ecause of the existence of this surplus 
whose tendency is to supply sufficient timber of a larger age, i.e., to raise the minimum 
exploitable age. This might be set, for instance, at r — ^cc years instead of r — cc years. 

This process contains the key to the regulation of the cut in transition forests in 
order to equalize the yield during the cutting cycles in which the surplus is being 
disposed of. The greater the surplus, and the shorter the cycle, the nearer can the 
minimum exploitable age coincide with the rotation age r. Conversely, with a fixed 
cycle, the higher this minimum age or size is placed, and the nearer it coincides with 
r years, the more timber will be left per acre, the more surplus will be carried over 
to the second cutting cycle and the more the cut will be evened off as between successive 
cycles while the surplus is being removed. 



Cutting Cycle in- Regulation 1T7 

124. Desirability of vShort Cutting Cycles when Possible. It is evident 
that from the standpoint of the forest, in order to reduce waste from over- 
maturity, carry over and distribute the surplus, break up the cutting areas 
into smaller units and reduce the volume required in the felling series to a 
negligible factor, a short cutting cycle is indicated for transition cutting, 
and only the necessity of harmonizing the methods of regulation with unavoid- 
able economic factors (§111) will force us to adopt long cutting cycles for 
the present on some of our forests.* 

With the short cutting cycle the allotment principle can be adopted (first 
illustration §115-116) as the basis of calculating the cut, especially in forests 
which have already been partly or entirely cut over and now consist of culled 
stands and second growth, with small residual tracts of original growth^ 
as in many of our national forests in the Appalachians and White Mountains. 

125. Necessity for Horizontal Cut and Long Cutting Cycles on Virgin 
Forests. But where economic conditions require a long cutting cycle for 
the transition of a large area of original and overmature forest, the actual 
practical difference between the required standard of cutting in logging opera- 
tions and a theoretical allotment of definite stands or size classes becomes 
too great to be ignored, and the allotment of cutting areas and calculation of 
the annual cut must be made to conform with these conditions. The cut 
must be determined or limited on the basis either of area, or volume, or 
both. Apparently in the transition of a forest already normal, as in the 
illustration (§ 116), this method of horizontal cut would increase both the 
area cut over and the volume removed in the first cutting cycle to an excessive 
amount and be no better than the allotment plan in its ultimate effect. 

But we are not dealing with a normal forest. The two practical consider- 
ations which we face are the surplus in overmature age classes, and the 
decadence and loss occurring in these classes. 

As seen, the surplus tends to raise the minimum exploitable age, hence 
removes one objection to the horizontal cut, that of lowering the average 
age of cutting. 

Dctcnnining Influence of Factor of Decadence. But the real factor is the 
loss from decadence. A certain portion of the volume of overmature timber 
inevitably dies or is killed or destroyed annually in such forests. This reduces 
both the area occupied by the merchantable stands, and the available volume 
which can be cut during the cycle. If we falsely assume that this loss does 
not occur, and proceed on the allotment principle in fact, by progressively 
raising the age or diameter limits during the cycle (§ 115-116), both the 



* The cutting cycle on the western yellow pine type in Arizona and New Mexico 
was unconsciously lengthened from about 60 or 70 to 100 years by a change in the 
practice of marking, which removed a greater per cent of the mature yellow pine timber, 
and increased the cut per acre and, as applied in practice, lowered the average minimum 
exploitable age to between r — Mcc, and r — cc years by heavy marking in Blackjack 
age classes. The reasons for this change were the absence of silvicultural necessity 
for leaving ^ of the stand, the favorable effect on stumpage prices of increasing the 
cut per acre, and the avoidance of loss in leaving large valuable timber at time of first 
cut. There was also in many stands the necessity of cutting heavily to wipe out loss 
from mistletoe and disease. 



ii8 Ajiicrican forest Rci::;u}ation 

volume available for cutting and the area occupied by the assigned stands 
will diminish to the extent of this decadence, which in a cycle of ^ or ^ r 
will constitute a large per cent of the total available cut (25 per cent is not 
unreasonable). 

This unavoidable loss is accompanied by a natural reproduction which will 
be available in the next rotation, but not in the present one. For this reason, 
not only because of practical economic conditions of logging, but in order 
to apply common sense in regulating the cut and renewing the forest, the 
age and size classes which mature ahead of the sazvs during the first cutting cycle 
must be included in the cut for that cycle, by adopting the principle of a hori- 
zontal cut and felling reserve in regulation. 

126. Illustration of Application of Principles to Western Yellow Pine. To illustrate 
the effect of this principle upon transition forests we will assume a rotation of two 
hundred years for western yellow pine, and a cut of eighty per cent of the merchantable 
volume. This cut is heavier than will be necessary in the second cutting cycle, i.e., 
constitutes a larger per cent of the stand, because of the surplus of overmature timber 
present and resultant deficit of younger age classes. The growth predicted on the 
lemaining stand indicates a period of one hundred years as required to produce, from 
the twenty per cent of merchantable timber plus the maturing of young stock, a cut 
of sufficient volume per acre to justify logging operations similar in character to the 
original operations and the logging of timber which would otherwise be rendered inac- 
cessible. The cutting cycle is then fixed at one hundred years or ^ r. On an area of 
1,000,000 acres, the annual cutting area will be 10,000 acres. But on this area the cut 
actually covers but one half for the other half is occupied bj^ young timber and repro- 
duction. Actually then, 5,000 acres of mature timber is cut annually, and in two 
hundred years the tract is gone over twice but each acre of ground is logged clean 
only once. 

The average age desired is 200 or r years. If this forest were a typical many-aged 
form, and no overmature timber existed, the maximum age of the standing timber 
would at the start be 200 years, ranging down to i year, with an average age for all 
stands, of 100 years or ^2 r. 

But the actual age of the overmature timber is 300 years, and the average age of all 
stands is nearer 200 than 100 years. 

If the cut is determined on the allotment principle, the volume of the annual cut will 
be the present volume of the stands which constitute eighty per cent of the volume of 
merchantable timber, plus the net growth for one hundred years, on the age classes 
which make up this eightj'- per cent. 

The timber lost by decadence in overmature stands must be deducted from the total 
available cut. The area reproduced, as the combined result of cutting, and of replacement 
following natural losses in the stands, will or should be about one half the total area, or 
S,ooo acres per year. 

Effect of Substitution of Horizontal Principle. But if, in logging, the same diameter or 
age limitations are applied to the cut each year, and the principle of a horizontal cut 
is adopted, the following conditions are faced: 

1. If the total loss by decadence has been calculated and deducted from the total 
available cut, the limitation of the annual cut will be correspondingly reduced by i/cc 
of this amount. Now, unless the cut is actually confined to the allotted age classes, 
(if instead) the younger timber maturing ahead of the saws is cut as logging operations 
reach the areas, the additional volume thus available per acre slows up the progress of 
cutting if limited as above, and the failure to coordinate the calculated cut with 
operating conditions will result in a failure to complete the removal of the old timber 
in the desired cutting cycle. 

2. If on the other hand the amount of timber maturing ahead of the saws has also 



Cuffing Cycle in Regulation 119 

been calculated, and included in the possible total cut, the annual cut as calculated 
should agree with the volume which will be available, and the cycle will see the removal 
of the overmature timber as planned. 

By either plan, because the actual cut is on the horizontal principle, a felling reserve 
consisting of a cutting series of graduated age classes will be built up behind the saws, 
from the timber left standing, but in the latter case it will be of the required arrange- 
ment, with a maximum age equal to the minimum exploitable age plus cc years and 
containing cc age classes. 

It is not necessary, in the first cut, to remove from this forest in the first cycle all 
timber down to H r years in age, i.e., to 100 years. The preponderance of overmature 
timber may be such that the minimum exploitable age may be set instead, at 54 r. The 
second cutting cycle will take care of this surplus which is carried over. 

For illustration, assume that the average age of the timber to be cut is 250 years 
and the minimum exploitable age of 150 years or fifty (^ r = cc) years less than r years. 
If the principle of allotment is applied, the average age of the stands cut during the 
first cutting cycle would finally, in the last year, reach to 350 years, and the average 
age for the whole period or cycle would be 300 or r -f- cc years, with a coistant serious 
loss from decadence for 100 years. 

If we now include the additional areas which will mature ahead of the saws, during 
the cutting cycle of 100 years, this should amount to one half of the timber now 
between 150 (minimum exploitable age) and 50 years of age. 

Knowing the area of this young timber, this quantity can be obtained. If for 
instance, two thirds of the area of young timber below 150 years is from 50 to 150 
years of age, and the sum of these young age classes covers half the total area, then 
333<333 acres will mature in 100 years, one half of which will be on areas ahead of the 
saws and one half on areas behind the saws or on areas already cut over. Then 166,666 
acres of young timber should be cut and reproduced in the cutting cycle of 5^ r years. 
This increases the area of the annual cut by 33y3 per cent. The increase iii volume 
depends upon the rate of growth of the stands, and should be calculated from yield 
tables, as was done for the old timber. The total cut would be materially increased, 
the annual limitation of cut correspondingly increased, the decadent timber all removed 
in ^ r years, the surplus largely reduced and a felling reserve created containing timber 
from 150 to 250 years old. On the other hand, if the allotment idea is theoretically held 
to, the 150 year old timber standing on the last cutting area would not be cut in 100 
years when it was 250 years old but would go over into the second cycle and reach a 
considerably greater age before cutting. 

To sum up: 

The presence of a surplus of overmature stock enables a transition cutting to be 
carried out with a minimum exploitable age higher than r — cc years. But if the allot- 
ment principle of calculating the annual cut is applied, this in itself results in slowing 
down the cut and holding over the standing timber to a greater average age. The 
proper minimum exploitable age is best calculated when the annual cut is made to 
include the timber reaching this minimum age during the period. 

127. Basis of Computing the Annual Cut by the Principle of a Horizontal 
Cut. Siunniary of Previous Conclusions. It has been shown that the cutting 
cycle is merely the last period in the rotation coinciding with the period 
between the minimum exploitable age and the normal age of cutting; that 
in a transition cutting, either from one normal forest to another, or from 
an unregulated forest to a regulated form, a rearrangement of age classes 
takes place, creating a felling reserve for the succeeding cutting cycle; 
that this felling reserve is the apex of the triangle or final group (see fig. 6) 
in a complete series of age classes required by a normal forest ; that in the 
first' period, the presence of a surplus enables the transition cutting to take 



I20 " American Forest Regulation 

place by placing the minimum exploitable age at r — >^ cc years, and tends 
to secure an average of r years or over; and that after regulation, the cutting 
age of all stands cut can be r years. 

Relations of Grozvth to Cut in Normal Forest. The calculation of the possible 
cut for the cutting cycle is based on very simple principles which relate 
directly to the desired normal series of age classes created by progres- 
sive cutting. These are, 

I. a. The cut from a normal forest for the rotation is just equal to the 
total growth during the rotation. 

b. If the growth is (incorrectly) assumed to be laid on in equal annual 
quantities, then the growing stock required to maintain an annual cut is just 
y2 of the total growth or of the total cut for the rotation. 





Felling 


Surplus 


^^ESIDUAL 


/Reserve 




^^rowingStock 










' 



Fig. 6. — Illustration of Residual Growing Stock, Felling Reserve and Surplus. 



c. The average age of this growing stock at any time is J/^ r years. 

d. The period which the average stand will remain before being cut 
is 3^ r years. The growth put on is the growth for ^> r years. The cutting 
period is r years. 

Analogy with any Lesser Period as a Cutting Cycle. Allotment of Timber 
Now Mature. 

2. These same relations hold good for any lesser cutting period, such as 
a cutting cycle, as follows : 

a. The timber which may be cut during a cutting cycle under the 
allotmei^t plan, consists of all the timber now above the minimum exploitable 
age or size. This constitutes in an unregulated forest, the felling reserve 
I)lus the surplus. 

b. The timber below this age, or residual growing stock, coincides 
witli the age classes of a normal forest below the minimum exploitable age. 
This division may be indicated as follows : 

c. During the cutting cycle, the stands allotted for cutting, i.e., those 
that are ripe at the beginning of the cycle, will be cut progressively, so that 
the average period elapsing before cutting is ^^ cc years. 

d. The average growth put on by these stands is therefore either 



Cutting Cycle in Regulation 121 

tlie growth for ^A cc years, or yi the growth for cc years, which is not the 
same thing. These two ways of expressing the growth are more nearly the 
same for any period or cutting cycle of less than r years than for the rotation 
as there is not so much diversion between current and mean annual growth 
for the shorter period. The latter method of calculation can therefore be 
adopted, and is universally used in European regulation to determine the 
total growth available for cutting. 

e. The total volume available for cutting from stands allotted to the 
cutting cycle at the beginning of the period is then 

Volume -|- Growth for ^^ cc years. 

3. In practical operations, on a large area and with a fairly long cutting 
cycle, all trees which reach the minimum size or age during the cycle, and 
on areas which have not yet been reached by the progressive cutting opera- 
tions, will be cut with the remaining mature stand which constituted the 
original volume above this size or age. 

If it were possible to cut all the mature stock above the exploitable age 
in one-half the cycle, the growth realized on this stock before cutting would 
be 3^ of ^ of the total growth, or ^ ; ^ because of the reduction in length 
of the cutting period, and only 5^ of this because of the serial progression 
of cutting which reduces the period elapsing before cutting to half of the 
cutting period. Again, if the maturing stands could all be cut in the last 
half of the cycle, the growth on these stands would be ^ plus %, the first 
half because no cutting occurs for half the period and the remaining Y^th. 
because of the serial progression of cutting. Thus the sum of the growth 
realized on both classes is roughly y2 of that on all stands cut. 

Because of the fact that both the mature and the maturing stands are 
cut simultaneously throughout the period, the growth realized on the mature 
stands instead of being %t\\ will be ^A of the total, while that on the maturing 
stands will be less than %ths and will more nearly approximate ^. Actually, 
it will slightly exceed ^ in a forest of all ages, since even with progressive 
serial cutting, the larger portion of the maturing stands will mature in the 
latter half of the period. Therefore the assumption that ^ of the growth 
will be cut is conservative and practical. 

By fixing the minimum exploitable age at r — 1-2 cc years, the stands which 
will reach this exploitable age in cc years will be all those ranging from 
r — ^ cc to r — ij/2 cc years at present. Of those stands, a volume equal 
to ^ the total, or approximating those now r — ^ cc to r^ — cc years will 
be cut, plus 3^2 the growth on these stands. The remainder will constitute 
part of the felling reserve for the next cycle. 

The cut for the first cycle can then be recast as follows : 

1. Volume of all stands above r years plus ^ growth for cycle. 

2. Volume of all stands from r to r — cc years plus y^ growth for cycle. 

or. 

Volume of all age classes down to r — cc years, plus ]/> growth for cycle. 

It is thus seen that the one essential step in securing a horizontal cut, 

and in calculating the volume and increment of the stands to be cut, is to 

get the minimum exploitable age at r — 3^ cc years, which step will permit 



122 America)! forest Regulation 

of the formation of a felling series and felling reserve during the first cycle 
whose average age is r — ^ cc years, and whose age, when cut, will aver- 
age r years. 

The cut for each progressive cycle will then equal the volume of all trees 
above r — cc years at the beginning of the cycle plus J^ the growth for the 
cycle, the minimum exploitable age being retained at r — yz cc years, until 
the forest has been completely cut over, which will require a full rotation, 

128. Quiz. What three preliminary conditions are required to permit of undertaking 
sustained yield management? 

How does the character of our forests make regulation difficult? 

What is the cause of overcutting? 

What classes of growth data are required? 

What classes of owners should practice sustained yield? 

What cutting policy is indicated for other classes of owners? 

What is the danger in such a policy? 

How is this danger to be avoided? 

Contrast sustained yield, destructive lumbering, and preservation of forest from 
destruction as goals for private management; and for public management. 

What is the eflfect of costs of logging on the required initial cut per acre? 

How do the demands of silviculture influence the initial cuts? 

Define the term cutting cycle. 

What three factors determine the length of a cutting cycle? 

What bearing has growth on cutover land and growth on virgin forests, respectively, 
on the length of cutting cycles, and amount of the annual cut? 

How does the cutting cycle differ from the rotation? 

What is the relation between the cutting cycle and the cut per acre? 

What element of forest regulation is affected by the length of a cutting cycle? 

Describe the differences and similarities of forests composed of even-aged and many- 
aged stands. 

Define the terms residual growing stock, and felling reserve. 

Compare a normal forest of even-aged stands with one composed of many-aged 
stands. 

Describe the effect of cutting these forests on a lo-year cutting cycle. 

Define the term, minimum exploitable age. 

What is the relation between the cutting cycle, the rotation, and the minimum 
exploitable age? 

How will the ultimate form of a forest be determined by the cutting cycle? 

How is the theory of the allotment method departed from in practice? 

Describe the principle of cutting termed the horizontal cut, and its effect in creating 
a felling reserve. 

What effect does it have on the surplus, normal growing stock, and average age of 
cutting? 

How are the allotment principles and those of the horizontal cut illustrated in con- 
tracts for the purchase of timber stumpage for future cutting? 

Describe the effects of surplus of over-matured timber on the determination of mini- 
mum exploitable age. 

How can this surplus be thus distributed in point of time? 

What factors indicate a choice of short cutting cycles in virgin forests? 

Why do long cutting cycles require a horizontal cut? 

What effect has the factor of decadence in virgin forests favoring the adoption of 
liorizontal cuts? 



CHAPTER XI 

THE APPLICATION OF REGULATION TO AMERICAN FORESTS 

129. Resume of Principles, i. The management of American forests 
must be based primarily on protecting and continuing the productiveness of 
forest land, and in this form it is applicable to all classes of owners. 

2. The regulation of the annual cut to attain a sustained yield is not 
always possible and can be attained only when both the economic and physical 
conditions are favorable. 

3. Market conditions and the cost of transportation and logging as 
reflected in stumpage prices, combined with the silvicultural demands of type 
and species as influencing reproduction and health of the stand, will determine 
the character and per cent of the initial cutting per acre, and cannot be 
materially modified. 

4. The per cent of the stand which is cut and the resultant rate of growth 
upon the cutover lands, taken in connection with the future conditions of 
logging and transportation, will determine the period which must elapse before 
the second cut. This period is the cutting cycle. 

5. The total available cut of mature timber as determined by the area, 
stand per acre to be cut, and growth available before cutting on these stands, 
will indicate the limitation of the annual cut required in order to secure 
sustained yield. 

6. The same basic principles of regulation apply to forests of all forms, 
whether even-aged or many-aged. 

7. Wherever transportation conditions make forests readily accessible to 
intensive markets, short cutting cycles are adopted, and the principle of 
regulation most frequently employed is that of allotting a definite per cent 
of the mature timber by volume and by area, to be cut during the cycle. 

8. When, because of difficult transportation problems, forests are rela- 
tively inaccessible and a long cutting cycle must be adopted, the principle 
of a horizontal or progressive cut which coincides with the method of cutting 
actually applied on such forests must become the basis of calculating the 
amount of the annual cut and regulation of yield. 

9. This principle recognizes the fact that the cutting on successive areas 
will continue to require the same age and diameter limits as originally agreed 
upon, regardless of the growth and change taking place in the forest. 

10. This means the inclusion in the cut of all stands which reach the 
minimum exploitable age ahead of cutting on the specific areas. 

11. The apparent excess of cut which would result, both by area and 
volume, in this enlargement of the cutting areas allotted for the period is 
ofl:"set, for unregulated original growth, by the unavoidable decadence and 
death of a per cent of the stands, and by the resultant natural reproduction, 
which factors reduce the area actually cut over. 

12. The regulation of unregulated forests is a transition resembling in 



124 American Forest Regulation 

character the transformation of a regulated or normal forest from one form 
or grouping of age classes to a different form, such as would be made neces- 
sary by a change in the length of the cutting cycle. 

13. TJic ultimate form and arrangement of the age classes in any forest is 
the direct result of the cutting cycle adopted. 

14. TJie period represented by the cutting cycle is not an addition to the rota- 
tion, but is the last period in .the rotation. 

15. The transition cuttings under a given cutting cycle require the cutting 
of stands of less than rotation age, to a minimum age of r — j^ cc years, and 
require the holding of other stands to an age exceeding the rotation by a 
maximum of ^ cc years, even in a normal or regulated many-aged forest. 

16. The same range of ages for cutting is required in transition cuttings 
in an unregulated forest, — but in forests possessing a surplus of overmature 
timber, the minimum exploitable age in the first cutting cycle can be set 
higher, if desired, in order to conserve the surplus and prolong sustained yield. 

17. In either case the minimum exploitable age during this cycle should be 
just j/2 cc years less than the average age of the timber to be cut. 

18. The adoption of the principle of a horizontal cut in the first cutting 
cycle establishes in that cycle a cutting series constituting a felling reserve 
for the succeeding cycle, consisting of a series of age classes whose number 
equals cc years and whose individual areas equal the annual cutting areas. 

19. This felling reserve is created by the growth of the timber below the 
minimum exploitable age (size) constituting the residual growing stock, 
which growth causes this timber to mature or enter the exploitable age or size 
classes. 

20. The cut for the first cycle comprises the timber above the exploitable 
age plus half the growth on the entire forest during the period. 

21. The portion of the cut representing growth is made up from 3^ the 
growth on the above merchantable timber plus 5^ of the total remaining 
growth on the entire forest. 

22. This latter quantity is equivalent to ^ of the volume of stands entering 
the exploitable class and ^-2 of the growth for the period on these stands, or, 
the volume of all stands between r and r — ^ cc years plus J/^ their growth. 

23. Although the volume of stands entering the exploitable class during 
the period is equivalent to the growth for the period on all the remaining 
young stands in a normal forest, this is not true of an abnormal forest, with 
irregular distribution of age classes, and statement 20 must be modified by 
substituting statement 21 and 22, for the expression, ^ the growth on the 
entire forest for the period. 

24. For all forms of forest, regular or irregular, the cut for any cycle 
is equal to, 

a. The timber above the exploitable age, 

1). Plus all the volume occurring either as growth on this timber, 
or in the form of maturing timber entering the merchantable age class on 
areas before they are cut over. 

25. The volume and growth on timber entering the merchantable age class 
(above the minimum exploitable age) after the areas are cut over plus the 



Application of Regulation 125 

volume and growth which will mature before cutting, in the next cycle, will 
in a normal forest about equal the volume and growth cut during the cycle, 
and will constitute the next felling reserve for the succeeding cycle. 

26. The adjustment of annual cut over 2 or more cutting cycles to 
distribute a surplus, in transition cuttings, depends on the possibility of 
shortening the cutting cycle, raising the minimum exploitable age and dimin- 
ishing the per cent of the cut per acre in the first cutting. 

27. Actual logging operations in all classes, types and forms of forests 
in America will be governed by these principles no matter what theoretical 
basis is used to determine the annual limitation of cutting. The cut per acre 
will be the starting point, the recovery by growth will fix the desired period 
for the first cycle. Whether or not the forest is actually regulated for sus- 
tained yield will then depend upon the ability of the forester to limit the 
annual cut so as to bridge the gap. Only when the total annual cut, as deter- 
mined by the area cut annually from the zvorking unit, as well as the cut per acre, 
can be reduced to the indicated quantity, can a sustained annual yield be 
attained. But if the silvicultural limit has not been exceeded in the cut per 
acre, protection given, and reproduction secured, then continued production 
is assured on the basis not of sustained annual, but intermittent periodic 
yield, which in the long run will produce fully as large a total yield of wood. 
Only when the productiveness or reproductive capacity of the forest is 
destroyed or impaired is its ultimate total yield reduced or destroyed. 

28. The question as to whether a given forest unit shall be cut so as to 
prolong the existing stock in such a way as to produce from now on a 
sustained annual cut and revenue, instead of a much larger cut during a 
shorter period followed by a cessation of cutting until the forest recuperates, 
contains the gist of forest regulation and must be determined for private 
forests by self interest, while for public forests, public benefits will clearly 
point to a sustained yield where the economic factors permit it. 

130. Application of these Principles to American Forests, The concep- 
tion that forests of even-aged and of many-aged stands are afifected in the 
same manner by the above laws of cutting and growth, in the establishment 
of cutting series and felling reserves, simplifies the consideration of the 
application of these principles to American forests. 

131. Preliminary Cutting Cycles for Valuable Species in Mixed Forests. 
In cases where originally a single species is merchantable in a mixed stand, 
it is almost inevitable that later on the remaining species will become mer- 
chantable. In this case, the growth required will be the economic growth of 
markets and stumpage values. The first cutting cycle can not be based solely 
oil the period required to produce an equal yield of the given species, for 
the chances are that this single species, as the result of cutting in a mixed 
stand, will decrease in numbers and growth by suppression. The cutting cycle 
may be based on the combined factors of growth of the species in question 
and future merchantability of the remaining species. The total growth of 
the stand, not that of a fraction of it, is the only safe basis of regulation. 
Cutting cycles based on selection of species in mixed forests are strictly 
preliminary in character, rather than transitional, since an abundant volume of 



126 American forest Regulation 

Z'iri^i)! timber is left whose later transitional regulation constitutes the real 
prol)lcm. This problem is quite commf)n in tropical forests. 

Since the development of the market cannot be predicted, and the heavy- 
cutting of valuable species might lead to their serious reduction or extermin- 
ation,* the possible future growth of the residual stock of the exploited 
species after cutting, and the period which would be required to obtain an 
equal cut of the species in the future might be used as a guide for determining 
the total cut, which could then be regulated to extend over this period, if 
sustained yield of the species is to be attempted. This principle of regulation 
was admirably brought out by Pinchot and Graves in the "Adirondack 
Spruce" (Gififord Pinchot 1898), for the Nehasane Forest, N. Y., although 
later research shows that the rate of growth after cutting fell short of their 
predictions on account of the severe competition of the hardwoods in mixture. 
The original cut of spruce which was completed in a very short period and 
was intermittent rather than sustained since the desired concentration of 
the annual cut required this and the overhead cost for a smaller annual 
output would have made the extension of the cut over the period 1896-1916 
unprofitable. 

132. Transition Cutting Cycle, Example of Intermittent Yields under 
Private Management. The real transitional cutting on this tract is now 
taking place. Now the problem is, to determine how long it will take the 
residual forest, cut for hardwoods and spruce, to recover so as to produce 
a yield which would justify a third cut whose volume will approximate the 
average productiveness of the forest. This tract is in the hands of an owner 
who is independent of the necessity of sustained yield, and no efifort is being 
made to find out what this cutting cycle should be, but the tract is being 
logged over on a cycle evidently much shorter than would be required to 
sustain the cut, much as a lumberman would operate. To reduce this oper- 
ation to a regulated annual cut and income, the rates of growth must be 
determined for hardwood stands left in the condition of these cutover areas. 
Such data are not at present available. But if the proper per cent per acre 
of the stand is being cut to secure the best growth and reproduction, criticism 
can be made of the operation only on the basis of the scheme of regulation 
adopted, and regulation for sustained annual yield in this second cutting cycle is 
optional with the owner just as it ivas in the initial cutting cycle for spruce. 

Under government ownership, the first step now, after fixing the limits of 
cut per acre and the species to cut and products to sell, would be to find out 
at once what is going to happen on that land, before contracting for the sale 
of so much timber that the length of the period to complete the first cutting is 
already determined by the amount of the annual cut and sustained yield rendered 
impossible. The amount to cut must be fixed by the period, volume available 
and growth, or the cut will be intermittent. 

Regulation, therefore, presupposes some definite knowledge of grozvth of 
stands and areas, not merely of single trees,** growth of average stands, not 



* As a result of cutting and of fire protection, teak is not maintaining itself in many 
Indian forests. 

** See Forest Mensuration, pages 315 to 455, H. H. Chapman, John Wiley & Sons, 
1921. 



I 



Applicatioii of Regulation 127 

merely of normal or selected fully stocked stands, and growth of cutover 
stands, not merely of stands in the original forest. This knowledge can be 
obtained, and to try to regulate the forest without it is a poor makeshift, 
but not so bad as failure to regulate it at all. 

133. Assumption that Growth Balances Decadence, The previous dis- 
cussion has shown that the straight allotment plan of regulation of the cut 
will give too small a cut if the loss from decadence of the timber is known 
and properly deducted, and that to offset this factor the volume entering 
the exploitable class by growth is included in the cut, by including the 
volume of trees falling in an additional class equal to ^2 cc years. 

The determination of loss from decadence is admittedly difficult. Few 
successful attempts have been made to measure it though it is possible to 
do so. Owing directly to this fact, such efforts as have been made so far 
to determine the total available cut for the first cycle in a transition forest 
have usually been based on the balancing of one error against another. This 
is, the assumption that growth in such virgin stands exactly balances loss 
from decadence and that therefore there will be no net change in volume of 
this timber above the exploitable age on the average acre during the cutting 
cycle. 

This conclusion is probably a conservative one, since to offset the loss on 
decadent timber we have not only the net growth on the age classes already 
mature or ready for cutting, but will add to this the volume and growth 
of one half of the maturing age class as well. The trouble is, that it may be 
too conservative, and fail to indicate the true amount of the available cut. For; 
a preliminary period of cutting, and for forests where the market or possible 
cut is probably below the permissible cut, this assumption might be as 
acceptable as any other since there is no danger of overcutting. If the rate 
of growth ascertained on cutover areas has indicated a cutting cycle of 
^ r years, the cut per year would then be x per cent (the cutting per cent) 
of the total merchantable stand above the exploitable age or size, divided 
by 3^ r years. Since the Von Mantel formula calls for a cut equal to 

total merchantable volume ^, , , , , , 

the above result would be more conservative 

than that obtained by this formula for an equal cutting cycle. If the cutting 
cycle were found to be Y^v ov y^v years the cut per year would be decreased 
proportionately. But the crude Von Mantel's or the Austrian formulae both 
differ from this assumption in that both take for granted that the forest is 
under management, has no decadent stock and is therefore replacing the 
grozving stock rapidly by growth, and for this reason, that the entire present 
stock can be removed in >4 r years or less, without depleting the forest 
capital. With an absolutely stagnant stock, only the fact of overmature and 
excessive volume, and the desire to rapidly replace this stock with a young 
growing stock, would justify such an assumption. 

134. Formula for Regulation of Cut Based on this Assumption. This 
formula for the annual cut may be expressed as 

Annual cut — ^% Q^ merchantable volume ^_ exploitable volume 

cc cutting cycle 



128 American forest Regulation 

The basis thus indicated becomes safer, the shorter the cutting cycle is made 
and the smaller the per cent that is taken, since the x per cent then applies 
more nearly to age classes on which decadence and growth for the period cc 
is apt to balance. This idea is practically the same as that of the French 
method of 1883, in which the cutting cycle, based on growth, was first fixed 
at ys r. the exploitable age at ^3 r and the per cent to cut at ys or 62^/2% 
of the merchantable stand. (§ 87) 
Then if Ga = Merchantable growing stock 

Annual cut = -^^ 

yr 

The later addition by the French of grow^th of the veteran stands before 
cutting, to ol:)tain the total permissible cut, is an attempt to get closer to 
the actual cut by studying the growth of mature age classes. 

135, Illustration — Coconino National Forest. The application of this method, and 
comparison with other formula methods, to the actual conditions on the Coconino 
National Forest, Arizona will bring out its characteristics. 

Merchantable growing stock 3,151,147 M ft. 

Area, 554,560 acres. Species, Western Yellow Pine. 

Area cut over, 116,137 acres. 

Net area of original forest 438,423 acres. 

Average stand, on uncut area, 7,194 bd. ft. 

Based on conditions of accessibility, and the silvicultural demands of the species, 

and upon the measured results of past cuttings, the per cent of the stand to cut is 

fixed at 80%. 

Based on the average yields per acre, and the products desired, the rotation is fixed 

at 200 years. 

Based on the rate of growth of the stands left on cutover lands,* and the stand 

required per acre to justify a second cut, the cutting cycle is fixed at J4r or 100 

years. 
Assuming no further knowledge of the composition of the stand, or the growth of the 
original forest, the cut will be. 

By the formula, Annual Cut = 

cc 

, , ^ , .8o(3i5ii47M) 
Annual Cut = ^^ 

= 25,249 M 

136. Comparison with Von Mantel's Formula. Von Mantel's formula is 
based on the theory, not that there is no growth on the mature stand, but 
that this stand is growing and will be cut and replaced by growth, and that 
it now constitutes a serially arranged felling reserve. Since the relations of 
grow^th and growing stock on such a forest are, 

Growth in r years = Cut in r years 
Merchantable stock = y^ Growth or 1/2 Cut in r years 
the cut per year on this forest would be 

Ga 



Annual Cut = 



_ 3151147M 
100 

= 31.511 M ft. 



* This rate was conservatively set at the rate realized on the original stand. Further 
study may indicate a dependable increase in growth after cutting. 



Application of Regulation 129 

This comparison indicates that it is unsafe to neglect the factor of growth 

on the mature timber, or of the volume added by maturing stands, in a long 

cutting cycle. 

Effect of Sliortening the Cutting Cycle. The effect of shortening the cycle, 

based on increased rate of growth after logging, or upon decision. to require 

a smaller stand per acre in the future as the basis of continuous cutting, is 

shown in the above case as follows : 

cc = ys r ^ 6y years 

* .80X3151147M 

Annual cut ^ 7 

67 

= 37,685 M 

which exceeds the cut by Von Mantel's formula, while if ^ r or fifty years 

could be used, the cut would be 

A 1 , .80X3151147^1 

Annual cut = ^^-^ 

50 

= 50,498 M. 
Hence, by shifting the Icjigth of period over which the present merchantable 
volume is to be spread, the annual cut obtained in the first cutting cycle can 
be greatly modified. The determination of the amount of cut which the 
forest will yield annually without overcutting, and which will bridge the gap 
between first and second cutting cycles so as to actually produce a sustained 
yield, is not a question of formulae or mathematics at all but an attempt to 
predict the results of living forces over a long future period. On the sound- 
ness of the observations and measurements of growth on which we make 
this prediction will rest the success of our efforts. 

In both France and Germany the policy is to be sufficiently conservative 
so that whatever mistakes they make in their predictions, the cut will not 
exceed the rate of growth actually realized, and the growing stock will 
increase. With our decadent and overmature forests, such conservatism 
during the transition cycle is wasteful, for natural agencies are sure to reap 
what man spares. 

The conclusion is that we should not be satisfied with crude guesses as to 
this cutting cycle, and should seek means of actually predicting the growth 
or decadence of the timber, not only that which is left after cutting, but in 
the original forest as well. 

137, Illustration — Munger — Western Yellow Pine in Oregon. First Cutting Cycle. 
The best example of an attempt to formulate a plan of regulation of the cut suited to 
American transition cuttings is that discussed by Munger.* The conditions assumed 
are, 

Species, Western Yellow Pine — Oregon. 

Stand, 16,000 bd. ft. per acre. 

Per cent to cut, 75%- 

Stand remaining, 4,000 bd. ft. per acre. 

Cutting cycle, 50 years 

Rotation, 200 years. 

Growth on cutover lands, 100 bd. ft. per year or 5.000 bd. ft. per acre in cc years. 



* FVoceedings of Society of American Foresters, Vol. X, No. i, page 18; see also 
§§ 70-71. 



130 Amcrica)i forest Regulation 

The area included within the working circle will of course determine the annual cut. 
To discuss the problem this must be assumed. If 200,000 acres is taken, the annual 
cutting area annually is 4,000 acres, over which 75 per cent of the stand is removed 
leaving 4,000 bd. ft. per acre as a residual growing stock. 

The cut for the lirst cycle of 50 years is based on the assumption of stagnation, 

expressed by the formula. Annual cut = — — and on the area, will be, 

cc 

A t . .75 X 16 M bd. ft. X 200,000 acres 

Annual cut = ^"^ -- 

50 
= 48,000 M bd. ft. • 

This is a cut of 240 bd. ft. per acre annually. 

The growth per acre annually, after cutting, is only 100 bd. ft. for 50 years. Includ- 
ing the residual growing stock of 4,000 bd. ft., the resultant stock per acre is thus 
reduced from 16,000 to g,ooo bd. ft. in this cycle by the removal of the overmature 
surplus. 

The method of cutting proposed is horizontal, i.e., to given diameter or age limits, 
thus creating a felling reserve by the growth and maturing after the saws of the stands 
now containing 4,000 bd. ft. per acre on areas cut over. The fact that an equal growth 
may be taking place on these same stands before the saws, is offset against the 
decadence of the virgin stands — it is also true that the rate of increase on this nucleus 
of 4,000 bd. ft. after cutting is probably greater than in the virgin forest before cutting. 
The growth on this 4,000 bd. ft. in the virgin forest was not studied. 

Second Cutting Cycle. Assumption of Normal Forest. This brings us to the end of the 
first cutting cycle. The one element which is based on research is the length of the 
cycle. The cut can be continued in the next cycle though at a reduced rate. Can it 
be continued indefmitely, and on what basis? To answer this question Munger assumes 
the existence of a normal (empirical) growing stock, based on the assumption that 
the residual growing stock of 4,000 bd. ft. per acre can be perpetually maintained, and 
that the growth expressed by the increase on these stands, of 100 bd. ft. per acre, 
represents the total annual cut possible. In each subsequent cutting cycle, under this 
assumption the cut is, 

Annual cut = 100 bd. ft. X 200,000 acres 

= 20,000,000 bd. ft. 
or s/i2ths of the cut permitted during the first cutting cycle. 
Analysis of Data. Felling Reserve. This conception must be analyzed for if sound it 
could be used widely in American regulation. In the present instance, with r = 200 
years, it is evident that the lower limitation of exploitable size or age was set at 150 
or r — cc years. In the first cycle, the average age and size of the merchantable timber 
was much above 150 and might even exceed 200 years. The felling reserve created in 
the first cutting cycle, however, will grow from 150 up to 200 years in maximum age, 
and will average 175 or r — K- cc years at end of the period, with an average stand of 
6,500, or 4,000 -|- 2,500 bd. ft. per acre. The cut, each year, is 5,000 bd. ft. per acre on 
4,000 acres (20,000 M bd. ft.), the ages ranging from 150 to 200 years on each cut. 
Groti'tli: The growth on these stands during the cutting cycle is. 

Present volume + (growth per year x J/2 cc years) 
or 6,500 + 2,500 bd. ft. 

This 2.500 bd. ft. or 100 bd. ft. per acre for J^ cc (25 }^ears) is the growth taking place 
ahead of the saws. The total growth is 5,000 bd. ft. and this amount is to be cut. So 
the other half; or 2,500 bd. ft. was what took place behind the saws in the last cutting 
cycle and is added to the residual growing stock of 4.000 bd. ft. In this second cycle 
2,500 bd. ft. or ]/> the total growth will again be put on behind the saws, and will in 
turn form the felling reserve for the future. 

But this "'growth" must be further analyzed to understand the state of the forest, 
and to comprehend how sustained yield is assumed. 

Correlating age and diameter we can assume that the stand of 4,000 bd. ft. of residual 



Applicafioit of Regulation 131 

growing stock per acre is less than 150 years old, or below the diameter limit of cutting, 
and that it represents the growth of this 150 year period. No trees of this class can 
be cut, Init all the trees of the class above, 150 to 200 years, are to be cut when reached 
in logging. But these latter trees are the same trees which in the previous cycle had 
laid on 4,000 bd. ft. of volume. Since the cut takes the whole tree, the 5,000 bd. ft. of 
growth (100 bd. ft. per year) to be cut must include such part of this 4,000 bd. ft. as is in 
the trees which mature plus the increase in size and volume of these same trees. 

The growth of 100 bd. ft. is evidently not the mere current increase alone on the 
trees to be cut minus the volume possessed by these trees at the beginning of the 
period. The average stand of 4,000 bd. ft. per acre is said to increase to 9,000 bd. ft. in 
50 years. Measured to the minimum exploitable diameter limit this 5,000 bd. ft. of 
"growth" to be cut does not comprise the current growth of the trees originally con- 
taining 4,000 bd. ft., but instead the total volume in 50 years of all the trees which grow 
out of this residual growing stock, which was too small to cut, and into the exploitable 
class, plus the current growth of these trees after they enter the class. 

Grozvth of Sef»arate Age Classes. Supposing that of this residual 4,000 bd. ft., 1,000 bd. 
ft. is from 50 to 100 years old, and 3,000 bd. ft. from 100 to 150 years. During the next 
50 years, this 3,000 bd. ft. grows into the 150 to 200 year class, and becomes 5,000 bd. £t. 
which is to be cut. It is evident that ^ of the cut was laid on before the period 
began, and 7^ only constitutes growth for the 50-year period on the trees cut. It is 
equally evident that the Vs growth is the total growth put on by the younger sizes 
during this 50 years, or by the rest of the forest or rest of the area, or remainder of 
the average acre, and that 5,000 bd. ft. is the growth per acre for 50 years not merely of 
the trees now mature, but represents the groivth of the forest as a whole. 

In practice, then, the difiference or increase in merchantable volume of the entire 
stand per acre correctly represents the growth on all classes of trees and all ages in 
a forest composed of a normal distribution of ages. (See §62.) 

But in predicting this growth, the analysis of the forest into its respective age classes 
will not only show clearly on what classes the increase occurs, but will show up the 
difference, if one exists, between a normal and an irregular distribution, instead of 
blindly assuming that the forest is already normal. 

Grozvth Per Cent. Lacking this data on age classes, it is customary to predict growth 
in terms of a per cent of existing merchantable board foot volumes. This disregards 
the effect of maturing age classes now unmerchantable. The per cent obtained is a 
function not merely of current growth but of volume on which it is laid, e.g., if the 
6,500 bd. ft. in the above instance grew even at 2 per cent for 50 years, a cut of 130 
bd. ft. per acre is indicated. 

The trouble with our efforts to devise means of regulating our forests is that there 
does not exist in the minds of American foresters or owners a sufificient background 
of knowledge of the composition of a forest, the influence of the distribution of its 
age classes, the difference in growth of these different age classes, or the relation of 
the successive maturing of age classes in determining the annual sustained yield. In 
this example (§ 137), the elements not determined were, first, the distribution of age 
classes: second, the per cent of total area occupied by the 12,000 bd. ft. of stand 
removed, and by the 4,000 bd. ft. left plus the unmerchantable age classes and repro- 
duction; third, the true growth per acre of these younger age classes, or the effect of 
maturing timber on the possible cut. 

As a result, while the outward form of the conclusions reached is sound, and a 
sustained yield of 100 bd. ft. per acre annuall)^ is indicated after 50 years, yet the actual 
indications as soon as we begin to analyze these assumptions may not bear out these 
conclusions. 

.Ictual Versus Assumed Age Classes. If the stand is actually from o to 200 years old, 
and in the form of a normal forest, four age classes of 50 years each must stand on 
each acre. Each year 4,000 out of 200,000 acres is cut, removing 20,000,000 bd. ft. But 
on this same 4,000 acres, three other age classes are present, occupying ^ of the area. 
The real cut is taken from % of each acre, or from 1,000 acres, and the stand on one 



1^2 Aiiwricaii forest Regulation 

full acre of this age class if segregated is 20,000 bd. ft., while on the second acre the 
stand would be 12,000 bd. ft. (4X3.000) — on the third acre 4,000 bd. ft. (4X1,000) 
while the fourth acre is covered by young growth. Consequently, the per cent to be 
cut, if a constant reserve of 4,000 bd. ft. per acre is maintained, will be but 5/9 or 
55 per cent as against 75 per cent, in the first cut. Unless these premises hold good, 
the assumption of 4,000 bd. ft. per acre as a residual growing stock is incorrect. 

But the most sweeping assumption is that after the removal of 'the excessive surplus 
in the iirst cutting cycle, the arrangement of age classes remaining is normal, as above 
indicated. The chances are that the overmature timber removed in the first cut really 
occupies more than 25 per cent of the area — probably also, the average age of the 
remaining timber may be greater than r or 200 years when cut, — and 2 cycles be 
required to reduce the surplus, or else the cycle chosen is too short. The plan, since it 
assumes norinality following the first cut, makes no provision for securing normality in case, 
as indicated, the actual distribution of ages is decidedly abnormal. 

Difference in Basis of Cut Bctivcen First and Second Cycles. In the French method of 
1883 (§87-88) after the cutting cycle and per cent of total volume to be cut has been 
theoretically computed, as H r and 5^ Ga respectively, no such assumption of normality 
is made. Were the original formula and method to be applied to the cut in the second 
cycle, as it was to the transition cutting, we would have the following comparisons — 
per acre. 

By method of 1883 

Annual cut = "^^^ >< ^^oo bd. ft. per acre _ g^ ,^j ^^ ^^^ ^^^^ p^^ ^.^^^ 
66 years 
By Von Mantel's = 6500 bd.f^ _g, ^^^ ^^ ^^^ ^^^^ p^^. ^^^^ 

100 years 
By Hunger's, basis oi % r and 5/9 Ga. 

Annual cut = '^S/^ ^ ._ -^ i^j f|. pgj. ^^.^g p^j. yg^r 
50 
But in the second cycle, with surplus removed, this »!cthod is already obsolete. The 
French assume an allotment of the upper ]^ of the stand for the period, and since their 
cutting cycle is not J/^ r but a period of but 5 to 8 years only, the felling series is not 
coincident with the cutting cycle at all, but is insignificant, and the actual average stock 
per acre of timber in the upper third of the stand should be ?^ of the total and not J^ 
of this, or 5,000 and not 2,500 bd. ft. above the 4,000 bd. ft. reserve, thus providing for 
an average cutting age of r or 200 years, with timber probably varying from r — J^cc 
or 196 to r + H cc or 204 years in age. Substituting 9,000 for 6,500 bd. ft. the results are. 

By method of 1883, annual cut=' — ^ — =85 feet per year per acre. 

66 

Recognition of Groivth in Second Cycle. Because of our long cutting cycle, this simple 

I'Vench allotment method will not work.* What Munger actually assumes is, that, 

although but 6,500 bd. ft. is on hand per acre, there will be 9,000 bd. ft. on the cutting 

area when it is to be cut, hence tlie annual cut = '55/2 X 9 — __ jqq ^^ f^ pgj. year. 

50 

The specific difference in management caused by the shorter cutting cycle can be 

further illustrated. 

With a cycle of 10 years instead of 50 years, the area cut over annually would be 



* We must bear in mind that the French method of 1883 is applied to selection forests 
of silver fir and spruce. They would never use the method for pine stands with groups 
of even-aged trees, nor would they calculate ahead for more than 20 to 30 j'ears. They 
are apt to discard refinements as immaterial to the result. 

T. S. W., Jr. 
We must also bear in mind that the reason that they would not do so is the possi- 
bility of a short cutting cycle, rather than the diflference in the silvicultural system. 

H. H. C. 



Application of Regulation 133 

20,000 acres instead of 4,000 acres, or i/io of the total area of 200,000 acres. The total 
cut b}' Munger's figures is 100 bd. ft. X 200,000 acres or 20,000,000 bd. ft. Concentrated 
on 20,000 acres, the annual cut per acre on the cutting area only is but 1,000 instead 
of 5,000 bd. ft. which means that only the trees which have fully matured need to be 
cut, and there is no felling reserve worth mentioning. The acre is cut 5 times in 50 
years, yielding 1,000 bd. ft. at each cutting. But with a cutting cycle of 50 years, this 
felling reserve and the growth which takes place during the cycle are the factors 
which permit of a cut of 5,000 instead of 1,000 bd. ft. per acre and since it is evident 
that but 6,500 bd. ft. per acre is present on the area as a whole (2,500 bd. ft. of which 
is mature), the assumption of a cut equal to 55 per cent of this stand for the cycle 

would not do. To get 100 bd. ft. per acre, 77 per cent must I)e cut. or ^°°° of the 
* 6500 

stand, — and 77 per cent can be cut, since it is cut annually on an area which has put on 

50 years' growth and contains actually 9,000 bd. ft. per acre, not 6,500 bd. ft. 

For these reasons, the formula, annual cut = ^''' -^cannot be used in the second 

cc 

cutting cycle, for gron'th iitust here be recognised as a material factor in the cut. 

Need for Determining Condition of Normality. The relation of volumes, as }i to ^A 
assumed by the French method of 1883, is not the relation actually existing in the forest, 
nor even that assumed to exist after one cutting cycle, but it is the theoretically 
calculated normal relation which should exist in a forest which has a normal form, 
regardless of the density or degree of stocking of each age class, — a normal arrange- 
ment on a basis of empirical stocking. The real work of regulation is to secure this 
relation in the actual stand, and this will be our problem in the second cycle and 
thereafter. But we rnust first ascertain as did the French, what is the normal pro- 
portion of volumes to be striven for, and what actual proportions exist in the forest. 
This calls for the separation of age classes in the forest, on the basis of age. area 
occupied, and volume produced or yield per acre, regardless of whether this forest is 
all-aged or even-aged in form. This same information is needed, not merely for a 
continuance of regulation after the surplus is cut, but for the initial determination of the 
cutting cycle, and of the annual cut. 

138. Summary of Principles. To sum up : a. Unless the species consti- 
tuting tlie main volume of the stand are merchantable, regulation of the cut 
in the first cycle is preliminary in form and confined to the valuable mer- 
chantable percentage, which should be treated if possible for a sustained 
yield, based on growth, — but this cannot always be done. 

h. When the main yield becomes merchantable and accessible, the first 
cutting cycle is transitional, involving the creation of a felling reserve, and 
is usually long, even up to ^ r years. 

c. Although the length of the period must be based on studies of growth 
on cutover lands, the amount of the cut in the first cutting cycle may for 
the present and in absence of proper growth data be fixed on the basis that 
the loss will balance growth in the virgin stands previous to cutting. 

The annual cut of timber now mature then becomes 

X%Ga . ■ 

* 
cc 

d. Current growth per year on the stand left per acre after cutting, if 
calculated to include the total volume of trees maturing or becoming mer- 
chantable, is sometimes assumed to indicate the sustained annual cut. 

But this assumes a normal forest, which does not exist in fact. 

We need to know the composition and yield per acre of the forest by 



134 America)! Forest Kcgiilation 

separate age classes, in order, first, to determine what is a normal forest, 
second, what is a sustained yield, third, what steps should be taken to attain 
these o])jects. 

After determining the length of the initial cutting cycle, and the per cent 
of the stand to cut, the general method of regulation, applicable to American 
forests is, 

1. The annual cut, during the first or transitional felling cycles should be 

a. X per cent of the present merchantable volume, which will consti- 
tute the exploitable age or size classes, which should be set at 
r — ^ cc years. « 

b. Plus the net growth in volume on these stands before cutting 
(total growth minus decadence), which is y^ the growth in cc years 

c. Plus ^ the total growth for cc years of the remaining stands in 
the forest including all age classes, which is equivalent to the 
volume and 3^ the growth for cc 3'ears on yj of the stands which 
would mature during this period cc, and is equal to all stands now 
between r — 3^ cc and r — cc years. 

2. The cut during the second cutting cycle should be, 

a. The felling reserve, which is the other half of the volume anc 
growth of the stands maturing during cutting cycle, 

b. Plus an additional quantity made up from the growth of the foresi 
during this period cc and represented by growth during this cyck 
on the felling reserve plus the maturing of stands into the exploitable 
class and growth thereon before cutting. In a normal forest thi: 

, would give a total approximately equal to the volume of the felling 

reserve. Together, these elements equal the volume at beginning 
of cycle, of stands between r and r — cc years, plus ^ the growtl 
during the cycle. 

3. The maintenance of the cut in subsequent cycles therefore depends 01 
whether the forest, after the first cutting cycle, is normal in distribution o: 
age classes. 

4. Regulation of the annual cut as between cutting cycles is impossible 
without a knowledge of the composition of the forest with respect to the 
area, age and volume of each age class, and a yield table based on empirica 
average yields for the forest unit. It is best accomplished by 

a. Ability to modify or reduce the per cent of the cut in the firsi 
cutting cycle and thus shorten the cycle and hold over the surplu; 
to the second cycle. 

b. Ability to reduce the total annual cut from the forest in case o; 
a long first cutting cycle so as to permit the accumulation of a large' 
cut per acre in the succeeding cycle. 

c* Ability to predict the cut of immature timber .and the proportiona 
area and per cent of the rotation which it will occupy. 
139. Separation of the Forest into Age Classes. The basis of separatioi 
of the stands comprising a working group is fundamentally age; — since tlu 
time required by growth will eventually govern the rate of cutting. In forests 
naturally composed of even-aged stands, which can be mapped and whose 
average age is easily determined, age will be directly ascertained by cutting 



Applicatioji of Regulation 135 

into sample trees, and the age classes can be separated by area and by volume 
for the forest during the forest survey. 

The separation of age classes in the many-aged form of forest cannot be 
made by area mapping, but must be correlated with average diameter — a 
principle sanctioned by the French in 1883 as the basis of their method of 
regulating many-aged forests.* 

Need for* Empirical Yield Table. Where age and yield per acre can be used, 
the basis of regulation becomes the yield table givijig volume per acre at different 
ages. But in the construction of this table, which is by selection of plots, it 
is neither possible nor necessary to attempt to secure average stands .or yields, 
which will represent the empirical or actual condition of the forest. Yet 
this latter data is what is required rather than selected yields which represent 
a liigher average of stocking, approaching "normality." 

Determination of a Reduction Per Cent. The principle which must be applied 
to solve this problem is to determine the relation of the volumes of the 
different age classes in the forest to the corresponding volumes for the 
same ages in the yield table, on the basis of equal areas. On this basis a 
reduction per cent is obtained and the yield of the age classes in the forest 
can then be gauged by the yield table after reducing this table to the empirical 
standard by applying this reduction per cent. If for instance an age class 
is now but 50 per cent of normal density its future yield will be computed 
at 50 per cent of the yield shown in the normal table. This basis is extremely 
conservative, since it is well known that sparsely stocked stands tend to 
close up with increasing age. 

There are several variations in the methods of applying this principle, but 
in some form it must be worked out for every forest on which regulation of 
yield is contemplated. The volume per acre of a given age class is a function 
primarily of age, and secondly of density of stocking. The three factors 
which must be determined, then, are age, area and volume. In the yield 
table, the normal relation of these three factors is shown, areas being stand- 
ardized as one acre. 

140. Summary of Possible Conditions, (i ) For Even-aged Mapped Areas. 
The different conditions encountered may be summed up as follows: 

Problem i. Even-aged mapped areas. Age, volume and area of each age 
class in the forest is directly ascertained. Usually true of regulated forests 
managed by clear cutting or shelterwood system, and can be found for sprout 
cuttings, or forest originating on burns. 

Solution. Divide the yield per acre of the age class by the yield from 
table. This gives the reduction per cent, separately for each age class, by 
which its future yield can be predicted by applying this per cent to the yields 
in the table for future years. 

For stands of less than merchantable age, this per cent of normality must 
be directly estimated by inspection, based on silvicultural knowledge of the 
stand.** For lodgepole pine, this normality per cent is reduced by overstock- 
ing a greater degree than by understocking. 



* Refer to § 87-8S. 

** Utilization and Management of Lodgepole Pine in the Rocky Mountains by D. T. 
Mason, Bui. 234 U. S. Dept. Agr., Page 36, Table 18. 



136 American Forest Regulation 

(2) For Even-aged Stands whose Volumes but not Areas are Known. 

Problem 2. Age and volume of each age class can be found. The area 
occupied is not separately mapped, Init the total area occupied is obtained 
for all age classes. 

Solution. This problem is easily soluble if it can be assumed that an 
average reduction per cent, applying equally to all age classes, will serve 
the purposes of regulation, as follows : 

1. Divide the volume of each age class by the yield of one acre of the 
given age, from the yield table. This gives the area which would be required 
by the age class if the stand were fully or 100 per cent stocked. 

2. Obtain the total of fully or 100 per cent stocked areas by adding! 
together the areas of all merchantable age classes. 

3. By comparing this area with the total area actually occupied by the 
sum of the age classes the density or reduction per cent would be obtained 
But this process disregards actual silvicultural conditions and young growth 
It is far preferable to 

4. Subtract from the total area the area stocked with young growth 
saplings, poles and seedlings established, — the residue is the area stockec 
with merchantable timber. Divide the "fully stocked" net area obtained a; 
above, by this net area stocked with merchantable timber. This gives th< 
density of stocking of the age classes whose volume can be measured. Thi: 
per cent is assumed to apply equally to all these merchantable age classes 

5. If the area "fully or 100 per cent stocked" thus obtained for eacl 
age class is taken as the basis, and is divided by the density per cent, thei 
the area in acres theoretically occupied by each age class of merchantabh 
timber may be found. This method of solution fulfills all practical condition: 
of regulation. 

141, Illustration from Tusayan National Forest. The volume of this stand has beet 
previously separated into veterans, mature, and blackjack, but the areas cannot b( 
separated directly in the field. 

Net area in timber, original growth, 52,004 acres. 

Deducted for saplings and seedlings, 13,002 acres — 25 per cent. 

Deducted for poles, 6,500 acres — 123^ per cent. 

Net area occupied by merchantable timber, 32,502 acres. 

Determination of the reduction per cent, or factor of density. 







Y 


ield per acre 


Area fully or 


Per cent of total 






from yield table 


100 per cent 


area in each 


Age class 


Age years 




ft. B.M. 


stocked* acres 


age class 


Veteran 


300 




18,200 


8,345 


58.3 


Mature 


200 




25,300 


1,745 


12.2 


Blackjack 


100 




11,300 


4,211 


29-5 



Total fully stocked 14.301 

Reduction or density per cent 

^^^^^ = 44 per cent 
32502 

Area in each age class. 

Ratio ^°° =2.2727 
44 



* obtained by dividing the volume in each age class in the forest by the yield 
shown in column 2. 



( 



Application of Regulation 137 

Veterans 8.345 X 2.2727 = 18,966 acres 

Mature i,74S X 2.2727 = 3,966 acres 

Blackjack 4,211X2.2727= 0,570 acres 

Poles 6,500 acres 

Saplings and seedlings 13.002 acres 



Total area 52,004 acres 

To predict the yield of these age classes, whose area and age we now have, the yield 
table must be reduced in this instance to 44 per cent of its original value. This 
assumes that stands now showing a density of 44 per cent of normal will continue to 
maintain this relation or better, and that if better the surplus is not considered. 

The yield table so obtained is a true empirical or actual average yield, adapted to 
the conditions of the forest or unit as a whole or to the type or working unit or group 
for which it was constructed. 

142. (3) For Many-aged Stands. Problem j. Volume and diameter are 
known but age classes cannot be directly determined. This is the typical 
form of problem for many-aged forests or forests in which the age classes are 
impossible of separation by area. The average age of different age classes is 
impossible of determination directly. Yet since age and the separation of age 
classes are fundamental to regulation, some means of separation and determi- 
nation must be found to permit of any systematic regulation whatever. 

Correlation of Diameter and Age. Solution. Diameters of the trees in the 
stands are readily determined. Diameter is a rough indication of the age of 
average trees. By determining the average relation between diameter and 
age, whether this be for total age or merely for current growth for a lesser 
period, the time factor (age) is supplied and the growth rate of the stand may 
be measured. 

The simplest principle of separation is that by diameter classes or groups. 
The rate of diameter growth is measured on a large number of trees to elim- 
inate individual variations. The curve of growth, to be accurate, should 
be actually based on diameter and not on age. The resultant table should show 
the average age of trees^of each diameter class. 

Owing to the period of suppression common to trees of tolerant species 
growing in many-aged forests, the absolute age of such trees is valueless for 
purposes of regulation, since the individual trees, if they had the benefit of 
sunlight or freedom from suppression, would mature without this period of 
delayed development. For this reason, one of two modifications are usually 
made in this curve — either the juvenile period of growth is omitted, and 
the table indicates the number of years it requires for trees of given sizes to 
grow to the next larger size, — or else if the total age is shown, this juvenile 
period is taken from trees which have not been suppressed. 

Function of the Yield Table. The yields per acre at dift'erent ages are now 
based primarily upon the sizes of the trees, their average volumes, and the 
number of trees of the given size which would stand on one acre of ground. 
The same relation as before exists between the normal or well stocked forest 
and the average or empirical forest. The yields for a normal or full stocking 
at different ages must be found, in the form of a yield table, in order to 
determine the normal relation or proportion existing between volumes on 
one acre at different ages, so that this relation or percentage of increase 



America)'. Forest Reinitiation 



from decade to decade, which is the law of growth of the stand, may then be 
appHed to determine the actual density of the forest in question, and to 
predict the yields of existing stands. 

For instance, in the French method of 1883 the relation of f^ to ^ which 
it was stated should exist between stands respectively over 2^ r in age, and 
between % and >^ r, was first found for an assumed "normal" series of age 
classes, in which the volume of the stand was calculated for the normal acre, 
and the average growth relation between the two groups roughly determined 
(§87). The establishment of this same relation is sought in the actual 
forest — its existence is the proof of empirical normality, independent of actual 
density. 

Derivation of the Normal Yield Table. From Crown Spread. This "normal" 
yield table, from which the percentage or proportional relation of stands of 
different ages or average sizes can be found may be worked out for our 
conditions on a sound basis in one of two ways. First, the average growing 
space demanded by trees of dififerent diameters may be found. Crown spread 
is almost always directly related to diameter, and is a direct indication in 
turn of the space required by a tree. If the proportional space per tree, for 
trees of different diameters, can be found, thus giving a curve of normal 
relations between number of trees per acre for different diameters, it makes 
no dift'erence whether on the whole this curve gives too many trees provided 
the proportion is correct as between classes, for it is as easy to reduce a table 
giving no per cent of the "normal" number, to 60 per cent as it is to reduce 
one giving 90 per cent, to 60 per cent. The volume of trees of these dimen- 
sions gives the normal yields per acre, while the age is taken from the average 
diameter. 

143. Illustration — from "Yellow Poplar in Tennessee" by W. W. Ashe, Bulletin 10 C 
State Geological Survey: 

Table 14. Number of trees in dififerent diameter classes per acre, required to obtain 
a continuous yield from a fully stocked group selection stafid of pure poplar. 

Approximate per cent of each 
Number of trees per acre 
Inches on average quality site 
280 
151 
57 
19 



Diameter classes. 

2-4 

5-8 

9-12 

13-16 

17-20 

above 20 



diameter class which should 
exist in a normal stand 

54 
30 
II 

4 
I 
.30 



513 

Ashe then states, "Since this table is based on fully stocked pure stands, it is neces- 
sary in the consideration of a mixed stand to ascertain the average number of trees of 
the different diameter classes per acre. The relation of this number in each diameter 
class to the corresponding table number gives the proportional annual yield which is 
to be expected from this diameter class when mature, that is when larger than 20 
inches." If in place of 19 trees to the acre in the 13 to 16 inch diameter class there 
were 6 trees, the proportion of stocking would be 6/19 as far as this diameter class is 
concerned. The annual yield per acre from a fully stocked stand is 430 board feet, 



r Application of Regulation 139 

k' _ . ' . . 

consequently the annual yield with the proportion of stocking given would be 

6/19X430= 135 ft. 

In this illustration, application of the principle of proportion or reduction per cent 
between a so-called normal stand and yield table and the actual forest is based on 
number determined directly by crown spread. 

The real difiiculty in this method lies in forests containing decadent stands of over- 
mature timber, for here, not only does the space required by an old tree exceed the 
propoition indicated by its crown as compared to a young tree, but the stand is losing 
its grip and is becoming open by the death of individuals. 

From Plots. For these reasons, the second method proposed below is 
preferable for such forests. This consists of actually laying out plots, in 
stands composed of trees of as nearly as possible the same size class, and 
determining on an area basis, which takes into account all the silvicultural 
factors affecting the stand, the number of trees on the acre and their average 
size and volume, and from this size, the age of the stand as in the first method. 

Once the table giving number of trees per acre for a normal stand is found 
for different ages, the results can be used to predict the yields even of mixed 
stands of hardwoods. 

In some form or other, this principle must always be used, and will serve 
as a means of applying to the exact conditions of stocking in the forest the 
laws of growth as ascertained by a special study of selected stands and 
trees. In the illustration given, the proportion between the number of trees 
of different diameters is the basis of comparison. In even-aged stands, the 
direct proportion between volumes is used. But the hnal result in each case 
is an empirical yield table adapted to the degree of stocking of the forest unit 
to be regulated. 

144. A System of Regulation of Yield, for Many-aged or Selection Forests. 
Based on Diameters and Diameter Grozvth. Preliminary in character, and dis- 
pensing zvith the yield table. Data Needed. The following data is needed : 

Stand table showing the number of trees and volume of each diameter 
class on the average acre in the forest. 

Table of growth of trees of different diameters, preferably showing number 
of years required to grow one inch. 

Volume table, based on diameter, applicable to the site class or average 
heights for the unit. 

The principle to be applied is explained in paragraph 127. A cutting cycle 
is determined on, which bears a reasonable relation to the rotation, and 
conforms with the required conditions of logging and silviculture. The min- 
imum exploitable sice or diameter is fjxed, which conforms to those conditions. 

The cut for the first cycle will include all trees above this size with ^ 
their growth during the cycle plus a volume equal to all trees in a diameter 
group below this size, whose scope coincides with a period equal to j^ the 
cutting cycle, to which 5^ the growth on these trees for the cycle is added. 

145. Illustration — with scattered shortleaf and loblolly pine growing with mixed 
hardwoods. (Southern States.) 

Cutting Cycle. On basis of logging conditions, condition of forest with respect to 
distribution of age classes, and silvicultural needs, the per cent of the stand to remove 
in first cutting cycle was set at 83 per cent and the minimum exploitable diameter limit 
which this called for in the cut, was 15 inches. 



MO America)} forest Regulation 

On basis of rate of growth of the trees in diameter, stand per acre desired on return 
cut. and number of years required to produce this yield from the existing forest, tlie 
length of the cutting cycle was fixed at 20 years. 

Calculation of the Possible Cut. — Calculation of Cut in first 20-Ycar Cycle. Average 
growth in diameter for Yi the period, or 10 years, 2.5 inches. Hence, trees maturing anc 
cut within period of 20 years, are those from 12.5 to 15 inches in diameter. 

X'olume of trees above 15 inches 1.408 M. bd. ft. 

Growth in 20 years (total growth less 15 per cent 

for losses) 403 M. bd. ft. 

Yi total growth is cut 201 M. bd. ft. 

Volume of trees from 12.5 to 15 inches 147 M. bd. ft. 

Growth in 20 years on these trees 248 M. bd. ft. 

H growth is cut 124 M. bd. ft. 

Total to cut within 20 years 1,880 M. bd. ft. 

Or, total volume of all trees above 12.5 inches 1.555 M. bd. ft. 

5^ growth in 20 years 325 M. bd. ft. 

Total cut 1,880 M. bd. ft. 

Calculation of Cut in Second Period of 20 Years. During this period, the age class from 
12.5 inches downward is to be cut. The diameter group includes 20 years growth. 
If the rate of 5 inches in 20 years holds good, this group embraces trees now 7.5 to 12.5 
inches in diameter. 

Twenty years growth during the first period brings this group above 12.5 inches. 
The volume thus maturing is that of the original group, plus 20 years growth, minus 
the losses occurring during the period. 

With the same minimum exploitable diameter as before, namely, 15 inches, this entire 
group will be cut during the next 20-year cycle, plus 1/2 the growth for this period. 
Volume, at end of period, of trees then above 12.5 inches, being 
the present volume of trees 7.5 to 12.5 inches, plus net growth 

for 20 years 790 M. bd. ft. 

Growth for next 20 years 400 M. bd. ft. 

K' growth, cut in next period 200 M. bd. ft. 

Total cut for second period 990 M. bd. ft. 

This general method is not based on cutting a definite number of trees (as in India 
for teak), but upon the volume produced by the existing forest, computed as usual 
by knowing the number and size of the trees in the forest. 

146. Factor of Loss of Numbers. The weak point in the method is the 
prediction of growth, based on number of trees which will survive. The 
actual net growth in any forest is the difference in volume of the separate 
age classes, found by comparing the n\erchantable volume of the live tree.- 
at one period with those of a succeeding period. A "normal" acre or stand 
table would help to indicate the progressive reduction in numbers with age. 
The improvement which this method evidently needs is the application of a 
yield table or guide in determining, at least, the loss in numbers, instead ol 
having to guess at this vital factor, (See Ashe's illustration, § 143.) Another 
great difference between forests under intensive management and primeval 
forests being brought under regulation is that in the former, the trees which 
normally die will be cut instead as thinnings or salvaged and are included in 
the yield, while in the latter, their volume at the beginning of the period is 
a net reduction from the total increase and is lost. 



Application of Regulation ' 141 

When it is necessary to predict this growth by measurement of growth per 
tree, applied to the total number of trees, as in the above example, the loss 
of trees must be offset against this growth in volume. In the example given, 
for lack of data, this loss was arrived at rather arbitrarily by deducting 15 
per cent of the final volume as lost during the 20 year period, this amount 
being 44 per cent of the assumed or indicated total growth had all the trees 
sur\ived. The diminution in number of trees, by diameter classes, as indi- 
cated in a stand table or a normal acre, would show the average loss in a 
normal many-aged forest in which no cutting whatever was done, and all 
trees eventually disappeared. In forests cut over at intervals, this rate of 
loss of trees is reduced materially. Graves, in the "Adirondack Spruce" 
claimed that on cutover land it could be ignored altogether. As it stands, 
the true growth realized depends, 

(a) upon the effect of cutting on the rate of survival of trees left after 
cutting, as well as upon their increased growth. 

(b) upon the ability of the forester to secure or salvage the trees which 
would otherwise be lost. This is largely a function of the conditions which 
permit of a short cutting cycle, the probability of salvage increasing as the 
cycle shortens. 

The true rate and amount of growth, when predicted from growth of trees, 
will fall somewhere between that indicated by survival of all trees, and that 
indicated by the diminishing curve of numbers of trees per acre based on 
diameter. Only a careful study of the composition of the forest with respect 
to growth will give accurate knowledge of this factor. In India it is approx- 
imated by guess based on the judgment and silvicultural knowledge of the 
forester. 

This data, taken from an actual stand on Henry Hardtner's forest at Urania, 
Louisiana, brings out some of the difficulties in actually bridging the gap 
between theory and practice in securing sustained yield on a forest not now 
under regulation. This stand had been logged once, removing large mature 
pines. The cutting cycle suggested is therefore in effect a second cycle — the 
first cut was to about 17 or 18 inches. In spite of the conservative (high) 
15 inch limit, leaving 17 per cent of timber now merchantable, the second 
20 year cycle gives a prospective sustained yield of approximately 50 per 
cent of that in the first cycle. 

147. Determining of Normality. To regulate or equalize the cut for these 
two cycles, which is evidently abnormal, a comparison could be made between 
the stands required for a normal forest and those in the actual forest. Data 
for this is lacking in the illustration. Granting that the 20 year cycle is the 
proper subdivision or period of the rotation, which for this forest is 80 years, 
we have four age groups of 20 years each. The average age of the mer- 
chantable timber in the second cutting cycle might be set at r — 3^2 cc or 70 
years, and the cutting age r or 80 years (§ 127). 

The approximate diameters are respectively : 

for 0-20 years 0-4" 

for 21-40 years 5-9" 

for 41-60 years 10-15" 

over 60 years 16" and over. 



14- American I'orcst Regulation 

The normality of the stand, if based on the 20 year cutting cycle to permit 
the maximum cut per cent per acre, would be determined by the volume 
available for cuttiiii^ in the successive periods, and not as in the French system 
of 1883 upon the present volume. 

Now, in order to confine the cuttin^^' during' the first cycle to trees now over 
60 years of age, or falling in the last period, the minimum exploitable age 
must be set at 70 years, and the diameter corresponding to this mark the 
minimum limit of cutting. This. l)y the relations explained in § 127 will 
result in cutting a volume equivalent to that of the 60 to 80 year 2nd class 
only, and will conform to a rotation of 80 years, reduce the cut in the first 
cycle by raising the diameter, and tend to equalize the cut from the first 
and second cycles. This method consists merely in adopting a short cutting 
cycle and a long rotation simultaneously. 

But the same general result ,can be obtained with a long cvitting cycle, 
provided the cut is actually prolonged to last throughout the cycle, and does 
not proceed to remove all the available timber within a shorter period. This 
means reducing the amount of the annual cut, and acreage cut over annually, 
to the proper proportion of the total available for the cycle. The same prin- 
ciples will apply in determining , the annual cut as were illustrated in the 
above example. 

148. Overcutting. The securing of a sustained yield and the mere prolonging*^ 
of the cut are tzvo different things. The latter is accomplished (as in the 
above illustration) if the second cut can begin in the year when the first 
cut terminates. But the cut in the second period is but 50 per cent of 
tliat in the first period (and in Munger's illustration. 42 per cent). The drop 
in production is partly due to the removal of an actual surplus stock accumu- 
lated by overmaturity. But it may also indicate actual overcutting.** For 
instance, in each of two or three successive cycles, the diameter limit may 
be lowered, thus holding up the apparent yield but at the expense of the 
forest capital which is being depleted. The level of sustained production 
must obviousl}^ be determined — a short cutting cycle based on supplementary 
cutting from forest capital is obviously an absurdity — for the "surplus" created 
by successively heavier per cents of cutting per acre in effect indicates succes- 
sively longer periods before the recovery of the forest or a second cut on the 
same area, and demands successively larger present quantities of growing 
stock or surplus if the cut is to continue throughout this cutting cycle. In 
mixed forests the successive cutting of diff'erent species as they become mer- 
chantable has frequently prolonged the ordinary logging operations over two 
or three cutting cycles, without in any way providing for a sustained vield 
in the end. The usual result of such overcutting is a final clean cut and 
abandonment of the enterprise. 



* Judging from data submitted to a bond house by a well known paper company such 
concerns, through vitally concerned with a sustained yield, are merely prolonging the 
cut. T. S. VV., Jr. 

** It is virtually paying unearned dividends (a) out of surplus so long as there is excess 
growing stock but (b) out of capital when this surplus stock is disposed of; (a) is good 
business while (b) is usually contrary to sound business principles. T. S. W., Jr. 



Application of Regulation 143 

In the above illustration, a reduction to 50 per cent of the first cut, on a 
15 inch cutting limit, may permit of continuing the cut every 20 years, on 
tliis reduced basis. Or the forest may be capable of a sustained output 
exceeding this figure. This would be the case if the 40 to 60 year age class, 
10 to 15 inches in diameter on which the cut and prediction of yield is based, 
were deficient in itumbers. Here again is where the normal acre, showing 
distribution of numbers, would serve as an indication. 

149. Method of Regulating Yield. To regulate or better distribute such 
a yield, the volume of the cut per year in the first period must be reduced, 
thus carrying over some of the surplus to the second period. This can be 
done by raising the diameter limit of cutting during this period, by one or 
more inches, thus shifting a portion of the cut to the second period. 

Beyond the first two periods, the distribution of age classes and regulation 
of the cut by this method is not feasible; nor would it be advisable. The 
numerical representation of trees required is subject to great reduction by 
suppression and other natural losses. Inspection is about as reliable as 
counting to determine the success of reproduction and degree of stocking by 
poles and saplings, and since the trees have no merchantable volume they are 
seldom tallied. 

Summary. For the regulation of many-aged selection forests, where it is 
impossible to determine age of stands from age of individual trees, age of 
stands must be determined from diameter of trees, by depending on the 
general laws of relation between diameter and age for trees. 

The cutting limit can correspond to a given diameter, and the volume 
available for cutting in the first cycle to the volume above this diameter, plus 
the volume of all trees which would reach this diameter in ^ the cutting 
cycle, plus ^ the growth on this total volume (§ 127). 

The cut in the second cycle will be equal to the volume of timber which 
at that time has reached the same diameter limit as indicated above, namely, 
a diameter representing an age ^ cc years less than that of the cutting limit. 
150. Comparison with French System of 1883. The annual cut can be 
sustained if necessary at a regular volume by raising or lowering the diameter 
limit* of cutting, based on comparison of yields thus secured in the two 
cutting cycles. 

A comparison of this general method with that of the French system of 1883 
shows that this latter method pays no attention to the quantity or enumeration 
of growing stock of the first third of the rotation leaving this to silvicultural 
practice, being assured it is probably sufficient (with the silver fir and spruce 
forests to which it is usually applied. T. S. W., Jr.). The actual stand 
table is completed for the entire merchantable stand. This is comparatively 
simple for us to secure, by assembling a stand table for the portion tallied, 
and expressing it as applying to the average acre. It is not necessary to 
tally every tree, either for estimating volume, or securing distribution of 



* The student of course must recognize the silvical disadvantage of strictly adhering 
to a rigid diameter limit; in practice mature trees below the limit are cut and youn| 
trees above the limit retained. 



144 



rhncricaii forest Regulation 



diameters. The percentage relation taken from a stand table prepared on 
a portion of the area will give this for the whole. 

The French, by a crude and inaccurate assumption (see discussion in § 87) 
arrive at the conclusion that if the second third of the area or age classes has 
three units of volume, the same stand in the third period should have five. 
This is based on the Von Mantel's principle that mean and current growth 
coincide throughout the rotation, hence the growing stock has the form 
shown below 





^^ 5 




^^ 3 


3 4 


^-^ \ 


1 2 


1 2 



and the removal of the entire volume on the last third of the area and rotation 
is possible in >^ r years. In practice, the volume of the upper third of the 
stock grows to the age of the rotation before it is cut, due to the short 
cutting cycle. 

Protests have been voiced against some of the methods here discussed for 
American regulation because said methods are not based on accurate math- 
ematical data and principles but ''pass from one assumption to another until 
the basis of accuracy is completely destroyed." If anything is more appar- 
ently inaccurate, and based on ranker assumption than this French method 
of 1883 it has not yet been found, yet it has worked successfully for thirty- 
eight years, and furnished a workable solution for the problem of regulation 
of many-aged forests.* 

Improvements Possible for American Application. Instead of basing the size 
or age classes upon the assumption that diameter growth is practically uni- 
form, and that trees of 1/3 the final average size required in the rotation 
are also Ys the age, — the same proportion holding for ^ — the actual rela- 
tions may be worked out from local growth studies. When the fundamental 
relations between size and age are established, the relations which should 



* It has been successful because there is frequent stock taking, because it has been 
applied by experienced foresters, and because there is good silvicultural practice in the 
forest with due regard to a proper distribution of size classes (without unnecessary- 
refinements). T. S. W., Jr. 



Application of Regulation 145 

exist between the volumes of the different age groups or classes can be 
obtained by these studies and the construction of normal acres. This period 
Ys V in the French system is independent of the cutting cycle and felling 
reserve. Here as repeatedly pointed out, the latter factors are too great to 
be ignored and the form and volume of the growing stock required must 
be computed with respect to the felling series. We cannot import a method 
even as simple and crude as this, without adapting it to our forest and 
economic conditions. The desire of American foresters for mathematical 
accuracy born in a large part from the lack of opportunity for the practical 
application of growth problems, can still be gratified to a considerable extent 
without splitting too many hairs. 

The progress of the forest towards normality of stocking, obtained by the 
French through conservative cutting, and by their curves showing the rela- 
tion of the number of trees per acre in actual versus normal forest, will be 
seriously delayed here by the removal of excess overmature stock, but can 
be secured by raising the diameter limit of cutting, where shorter cycles are 
possible, or by extending the length of the cutting cycle when the cut per 
acre cannot be reduced because of danger of blowdown or other silvicultural 
factors. 

Determining the AUoived Cut. Sustained yield in many-aged forests means, 
finally, the determination of the "allowed cut" or actual production per year, 
and the adjustment of the cut to leave the forest in shape to produce this. 
The reason for success with the method of 1883 is that the indicated annual 
cut, by the basis proposed, is practically certain to be somewhat, but not 
too much, less than the growth ; second, it effects a removal of surplus large 
stock, or its conservation as needed, and third, it increases only as the forest 
becomes more densely stocked through better silviculture. Until our over- 
mature and decadent stock is removed, conservative cutting should be based 
on cutting the smallest possible per cent of the standing timber per acre, 
and the largest possible cut per year which will enable us to cover the forest 
in one cutting cycle, which by the above considerations would be as short 
as possible. At best we will be forced to adopt long cycles on National 
Forests, where regulation is feasible. The stock needs reduction, and the 
worst problem is to secure better distribution of age classes or prevent the 
still further disturbance, by overcutting, of such distribution as may already 
exist. 

151. Summary of Distinctive Characteristics of American Regulation. 
The distinctive features of the method proposed, as applicable to all forms 
of forests in America, are : 

1. A period for regulation of yield, which is based upon and coincides 
with a cutting cycle. This may give place later to periods exceeding sl cutting 
cycle in length (provided the cutting cycles can be shortened so as to become 
a negligible factor), but never to be shorter than the required cutting cycle. 

2. The length of the cutting cycle to be the governing factor in determin- 
ing the regulation of the cut and to be based upon the existing conditions, 
forest, and economic. 

3. Regulation of the annual cut to be effected by lengthening or shortening 



146 American Forest Ref::nlation 

the initial or transition cutting cycle, corresponding to increase or decrease 
in the per cent of the stand per acre taken in the first cut. 

4. The amount of the annual cut to depend upon the cutting cycle, present 
volume, per cent to cut, growth of old stands and inclusion of the maturing 
crops of young timber entering the exploital)le class within the cycle. 

5. The result of the first cutting cycle to be the establishment of a felling 
reserve and cutting series of normal arrangement for continuance of the cut 
in the second cycle. 

6. Regulation of yield to be based on the use of a yield table and reduction 
per cent, the separation of age classes in the forest, and the prediction of 
empirical or actual growth, including decadence, on the age classes as they 
exist in the forest. 

The last requirement is so obviously in keeping with universal practice 
in forestry that only the assumed difficulties and expense of obtaining the 
required data has held back the science of regulation on our National Forests, 
and at present, the tendency is to go ahead at once with whatever data is 
available, to formulate some basis of regulation wherever it is needed. 

152. Quiz, ^\■hy are cutting- cycles for mixed stands preliminary? 
Why is a study of growth essential? 
When does growth balance decadence? 
Explain formula cited in § 134. 

Can the growth of mature timber be neglected in a long cutting cycle? 
Can the length of cutting cycle be guessed at? 
Discuss Munger formula; felling reserve. 
Why must age classes be analyzed? 
What is the danger of using growth per cent? 
Why must condition of normality be dete.'mined? 
Explain how empirical yield tables are necessary in regulation. 

How is a "reduction per cent" obtained for even-aged areas where mapped, and 
where areas are not separated? 

In all-aged stands how is diameter and age correlated? 

How is normal yield table derived from crown spread? from plots? 

How can the yield table be dispensed with? 

Explain a preliminary system of yield regulation for selection forests. 

What data is needed? 

Discuss complication of loss of numbers, normality, overcutting. 

Compare this method with French system of 1883. 

Enumerate essential distinctive characteristics of "American Regulation." 



CHAPTER XII 
THE PROBLEM OF SUSTAINED YIELD 

153. The Ultimate Problem — Sustained Yield. Owing to the importance 
of the prehminary and transition periods and the unavoidable disturbance of 
the forest capital and postponement of the creation of a complete series of 
age classes, the ultimate problem of regulation to secure that balance and 
arrangement in the forest which will permit of a permanent sustained cut,, 
is necessarily obscured. 

In the many-aged forest, as well as in that composed of even-aged stands, 
a rotation is fixed upon, which is supposed to coincide with the average age 
of the timber to be cut. Although the volume of the immature stands falling 
in the last third of this rotation is immaterial, the petiod required for them 
to grow to given sizes, and the area stocked by these young stands, is 
important. 

To finally determine ^^.•hether or not a forest is being over-cut; i.e., working 
capital instead of mere surplus is being withdrawn, we must determine three 
factors, all dependent on the rotation, — first, what the annual growth will 
be upon a normally arranged forest stocked at no greater degree of density 
than the existing forest, for this is the gauge of whether capital is being 
reduced ; second, the amount of actual measureable (merchantable) capital 
required to produce this quantity annually, and its arrangement by age 
classes as to volume and area, in each age class ; third, the comparison with 
the actual forest as to voluma and area, in existing age classes. 

The crude assumptions in the illustration in § 137 as to growing stock and 
age classes are plainly insufficient to show these facts. An annual growth 
of 100 feet per year on cutover lands may or may not be obtained continuously. 
A growing stock of 4,000 bd. ft. per acre may or may not constitute the normal 
reserve. The elasticity of the French conception of normal relations of 
growing stock between medium forest as ^, and old forest as ^ of the total 
merchantable volume, lies in the fact that it applies only to the form and 
relation of the two broad age groups, and equally to all degrees of stocking. 
This may be the only practical conception to apply to such forests, yet if 
possible, owing to the importance of the cutting cycle and the greater difficulty 
of our problem, a more concrete idea of possible sustained empirical yield 
is desirable. 

154. Allowed Cut, Empirical Yield Table and Normal Stock. This can 
be secured when it is possible to obtain an empirical yield table (by methods 
described in § 141) applicable directly to the degree of stocking in the forest. 
This the French did not attempt. 

With such a tal)le, the allowed cut of the forest is at once indicated. It 

• . r ^1 • 1 1 ^ ^. ^- f . v/ 4.U area in the working circle 

consists of the vield, at rotation age, of i acre X the : ^ 

rotation 

This yield equals the total growth of a forest of this density for one year, 

if normally arranged as to age classes, or, its equivalent, the mean annual 

growth on one acre X total area. 



148 American Forest Regulation 

On this basis, the normal growing stock can be computed, not by the 
method of approximating the residual growing stock below the size exploited, 
as being normal at 4,000 bd. ft. per acre, for instance, but from the yield 
table. An example of an empirical yield table is given below for Western 
Yellow Pine, Coconino National Forest : 

Table 15. Empirical yield table of Western Yellow Pine reduced from normal by- 
factor 66.2%. 

Scribner Dec C. Log Rule. 

Age 

80 

90 
100 
110 
120 
130 
140 

160 
170 
180 
190 
200 
210 
220 
230 
240 
250 
260 
270 
280 
290 
300 
310 
320 
330 
340 
350 
360 
370 

In § 135 the annual cut for the Coconino based on Von ^Mantel's assumption, 
was found as 31,511 M ft. 

Based on the assumption that the annual cut should equal the annual 
growth, the cut, for a rotation of 200 years and area of 509,087 acres at 
84 bd. ft. per year mean annual growth, would be 42,763,308 bd. ft. annually. 

i X r 
The growing stock required to perpetuate this cut would be, not —^ , Avhich 

(a + b + c+ +-f)io 

200 

i^8,qiq X 10 . . ^ r.^ .^ ^ . , 
acres 



Yield 


Mean annual growth 


Feet. B.M. 


Feet. B.M. 


4,700 


59 


6,220 


69 


7,480 


75 


8,610 


78 


9.670 


81 


10,660 


82 


11,580 


83 


12,510 


83 


13.370 


83 


14.300 


84 


15.090 


84 


15.950 


84 


16,750 


84 


17,540 


84 


18,070 


82 


18.270 


79 


17,940 


75 


17,280 


69 


16,350 


63 


15,360 


57 


14.300 


SI 


13.170 


45 


12,050 


40 


10,920 


35 


9,800 


31 


8,670 


26 


7,610 


22 


6,420 


18 


5.300 


15 


4,100 


If 



would call for 4,276,330 M feet, but -^ — — ^ X 509,087 

_ 138,515 X 10 ^ 509,087 (6,925 bd. ft. per acre) 



200 



Problem of Sustained Yield 149 

= 3,525,427 M, or approximately 80 i)er cent of that required by the formula 
iX r „ 

=r dn. 

2 

This determination of the real basis for a growing stock which would 
perpetuate the rate of growth now possible and realized in the past from the 
virgin forests enables us, first, to measure the actual growing stock to dis- 
coxer whether there is a surplus or deficit, and second, prevents us from 
attempting to reserve, as working capital, wood which is actually surplus. 

155. Comparison of Mean Annual Increment and Austrian Formula. Its 
Limitations. The mean annual growth of a stand to maturity rather than 
current growth per cent correctly gauges the increment for a stand which 
is cut since this cut takes, not the current increase from standing trees, but 
their total past growth, which is the mean annual growth times age of 
the stand. 

If the present stock exceeds or falls short of this normal growing stock, 
it is an indication that there is either a surplus caused by an excess of over- 
mature timber, or a deficit caused by past cutting, fires or other destructive 
agencies. It cannot mean that the indicated yield, or normal stock, is wrong 
since the actual past production of the forest itself has been taken as the 
basis for calculating this growing stock. 

It follows then that the Austrian formula, when based upon the empirical 
yield table to obtain the normal growing stock, and when the mean annual 
increment for the rotation age is used as the basis of increment, is an 
instructive check on the proper annual cut. The surplus, by our methods, 
should in order to save further loss be removed in one cutting cycle if the 
latter is fairly long. Cc, or at most 2 cc, becomes the period of regulation. 
Then 

Annual cut = mean annual increment + Ga — Empirical Gn 

cc or 2 cc 
Applying this formula to the Coconino: 

Annual cut = 42.763 M + 3i5ii47 M -3525427 M 

100 
= 42,763 M- 374280^ 

100 
= 39,020 M 

But applying the Austrian formula to current^^ growth as in Hunger's illustration, his 
empirical normal growing stock is first calculated as 

Gn = ( L}<SS. f Reserve) X area. 
2 

With total current annual increment in the forest, per acre, as 100 feet, and cc as 50 

years, reserve per acre 4,000 feet, 

^ 100 X 50 I ,„„ 

2 

^6.500 feet per acre. 

The actual growing stock is now 16,000 feet. Munger wants to cut 12,000 feet per 
acre on 4,000 acres or 48,000 M bd. ft. annually, on 200,000 acres, leaving the reserve of 
4,000 feet to grow to 9,000 feet in 50 years. 

By the Austrian formula: 

Annual cut = 100+ 16000-6500 (^^^^^ 
• 50 
= 290 bd. ft. per acre or 58,000 M bd. ft. in the first cutting cycle which 



150 American Forest Regulation 

is evidently excessive, due to the inclusion of growth in the formula which was not 
included by Munger in the first cutting cycle. Tlie Austrian formula is thus quite 
evidently inapplicable to this transition proljlcm on the basis of current growth on the 
cutover areas. 

The undertaking of regulation requires a .^utTicient knowledge of growth 
to indicate a rotation. Upon this basis, and the conception of a uniform 
felling series for even-aged stands, the empirical normal growing stock can 
be compared with the actual forest in order to separate the forest capital from 
surplus or deficit and obtain an indication of the amount of the required 
annual cut. 

The annual cut by any system of regulation will seek to remove an amount 
equal to the "interest" or growth, plus or minus an amount which will bring 
the capital either down or up to normal form within a reasonable period. 

When the true form of a series of age classes is not obtainable, a relation 
based on the growth of trees and broad age groups can be constructed, as 
done by the French in 1883, by which the surplus or deficit can be indicated 
as well as the growth. For our conditions, this relation should be based on 
the felling reserve and the influence of maturing crops of timber in deter- 
mining the cut. 

Whenever it is possible to determine this true form and volume of the empir- 
ical normal forest by means of an empirical yield table, and to base increment 
upon the mean annual growth from this table, the true relations between the 
empirical increment and surplus or deficit in the actual forest caused by abnor- 
mal age class distribution can be found, and the annual cut approximated by 
the Austrian formula check. Without this data the Austrian formula is no 
more accurate than Von Mantel's and if cc = >^ r and "normal" stock is taken 

r V i 
as —1^1— the two formulae will give identical results. 
2 

This pure volume check on regulation accomplishes in a rough approximate 
manner, what should be determined on a basis of definite knowledge of the 
forest, as soon as that knowledge is available. 

The utility and value of the Austrian formula is dependent, then, not on the 
formula itself, which is merely the expression of a sound principle of regula- 
tion universally sought, l)Ut upon the determination of the three factors, actual 
increment, empirical "normal" stock required by this increment, and the actual 
stock on hand. The cutting cycle then enables the determination of the cut 
per year. No knowledge of the age classes in the forest is required, and this 
is just where the formula fails. 

Every method of regulation seeks to establish this same result, but the dif- 
ferences between a practical plan and a formula check lie chiefly in recognitior^ 
of the fact that abnormality in volume is caused by abnormality in distribution 
of the respective age classes. Only by securing this proper distribution of age 
classes can the true normal \(tlume and sustained cut ever be secured. The 
growth actually laid on in the forest during a given cutting cycle is not the 
mean annual but the current growth, and this is dependent upon the age and 
condition of these abnormally arranged age classes. 

Bein^'" sound in theory, the Austrian formvila zvJieM based on facts as deter- 



Problem of Sustaijicd Yield 151 

mined by growth studies, does surprisingly well, but it is better to deal with 
the facts at first hand. In other words, since the regulation of the forest must 
be determined by the area, ^•olume and current growth of the existing age 
classes, the determination of these areas, volumes, and the actual current 
growth expected, will in turn indicate the area and actual volume of the 
annual cut best adapted to securing progress towards a normal forest. 

156. Necessity for Data on Age Classes. In the system proposed for many- 
aged forests, the present volume and actual current growth of the exploitable 
antl of the maturing age classes were found as a prerequisite of fixing' the cut. 
But for lack of data on areas, the yield for the entire rotation and the true con- 
dition of abnormality of the forest could not be accurately obtained which 
delays the progress toward normal forest and sustained yield. 

In choosing a method of working out this problem of sustained yield the 
silvicultural behavior of the species must decide. If the trees customarily 
undergo a period of suppression in growth, the age of individual trees gives a 
very unreliable index of the number of years required for an acre to produce a 
given yield in wood.* But if the species is intolerant, we have two distinct 
advantages ; first, the individual trees which survive and form the final cut 
are usually dominant throughout their life cycle and are seldom suppressed. 
Second, in spite of fires and other agencies, the forest tends towards even- 
aged groups, of varying size to be sure, but distinctly different from typical 
many-aged stands wdiich result from suppression and natural selection over 
a long period of struggle. 

157. A Method of Separation of Age Classes. The method to be described 
is applicable to intolerant species growing in stands of all ages in original 
forests. Since species susceptible to fire occur in even-aged stands and can 
be measured by direct yield tables, while tolerant species such as hemlock 
or spruce are subject to suppression, this method is especially applicable to 
Western Yellow Pine, Southern Longleaf or Loblolly Pine and similar species, 
^nd may have a wider application. For even in forests composed of tolerant 
species, many-aged, and mixed, the interference of fire, insects and wind 
constantly tends to produce groups of even age, and this fact can be taken 
advantage of to secure data for a yield table based on age, which will serve 
as a model or standard from which these essential relations of age and volume 
per. acre can be obtained even for all-aged stands. Owing to its great impor- 
tance in future regulation, the method of securing and applying such a yield 
table is given in detail. The species to which it was applied was Western 
Yellow Pine, but the method should be applicable, with suitable modifications 
of field tephnique, to nearly all our x\merican forests of mixed age. 

Essential Steps. The three steps in this regulation are: 
(a.) Securing the normal or standard yield table, 
(b.) Application to the forest to secure the empirical yield table and to 

separate the forest into age classes by area and volume 
(c.) Regulation of the cut based on area, volume and prediction of 

growth of these age classes, by use of this yield table. 



* Chapman's I-'orest mensuration §§ 263, 298, 299. 



152 American forest Regulation 

Standard Yield Table. Selection of Plots, (a) Yield table. The standard methods are 
followed in securing plots. These plots are laid off in groups or stands whose 
appearance indicated that practically the entire stand is of a given age class, though not 
necessarily of even age. A curve of average height based on diameter should be drawn 
for each plot or group of plots, preliminary to computing volume.* 

Where trees evidently of an older or younger age class are included in the plot, the 
crown space, or the proportional area occupied by such trees may if desired be deducted 
along with their volume to confine the results to a single broad age class. 

Determining Age of Plots. Age of the plots is best determined by felling at least three 
trees, selected to represent average volumes. But when the timber is very large and 
old, and is inaccessible to logging for the present, the felling is not only time consuming 
(increasing the cost of plot measurement by 300 per cent or more) but wasteful of 
timber, especially in the older stands. A substitute method of obtaining the age of the 
plot is as follows: 

a'. A curve of growth in diameter must he ol)tained from numerous stump measure- 
ments on logged areas. This should show the age at B.H. outside bark for average 
trees of giz'en diaiiicters. It is necessary that these growth figures be obtained for trees 
and stands of the same type and quality as the plots measured, else the conclusions 
regarding age of the plot will be in error. 

b'. The diameter of the average tree in the plot must be determined. In reducing 
stands of uneven age to their equivalent for an even-aged stand, the standard practice 
is to determine the age of an even-aged stand which will yield a volume equal to that of 
the uneven-aged stand in question.** The basis of volume must be the volume table 
and volume unit used in calculating growth. The first step in finding the tree of 
average diameter is to determine the tree of average volume from the total number of 
trees on the plot, and total volume. 

But as height is a variable, and the tree of this volume may be a tall tree with 
smaller diameter, or a short tree with larger diameter, we must first obtain the average 
height of a tree of this average volume, for the plot in question. The curve of average 
height on diameter for the plot has already been made for computing the volume on 
the plot, hence is available. 

With average height on diameter for the plot determined, there can be but one 
average diameter for a tree of a given volume on the plot. This is read from the curve 
of volume on diameter usually interpolated to i/io inch. 

The age of a tree of this diameter from the growth curve is taken as the age of the 
stand on the plot. 

Wherever site qualities can be separated, based on total heights of merchantable 
timber, and the curves of diameter growth obtained are coordinated with trees on these 
separate site qualities, this method has the double advantage of enabling the field crew 
to secure three times as many plots in a given time, and of basing the age of each plot 
upon a curve based on a large number of representative trees instead of but one or 
two trees which, on single plots in these uneven-aged stands may happen to be much 
older or younger than the real average desired. The stand not being truly even-aged, 
the advantage of felling single trees to determine age for the plot is much lessened, 
provided always that the growth data for the use of the alternative mettiod. is properly 
coordinated with the site. 

158. Application of Yield Table to the Forest, (b.) Separation of age classes in the 
forest. The problem is twofold, first, to find a method by which the age classes in 
the forest may be separated, second, to determine actual average density or degree of 
stocking for the entire area. 

Experience in former experimental attempts to solve this problem has shown the 
futility of trying to determine the area and volumes in different age classes on a large 



* See § 129 and 130, Forest Mensuration, John Wiley & Sons, 1921. 
**Ibid., §260. 



Problem of Sustained Yield 153 

area of this character by mapping the crowns, or by any direct method. Instead, 
dependence must be placed directly upon the volume of the stand, and its direct division 
into age classes by aid of our knowledge of the number of trees in the stand and the 
volume, diameter and age of average trees. 

The Stand Table. To obtain the number of trees in the age classes, the volume of the 
average tree and the total volume of the class, a stand table is required. 

This stand table is best obtained during timber estimating by any method which 
provides for a table of diameters. In estimating, it is accepted that strips covering 
5 to ID per cent of a large area give a sufficiently accurate per cent of the total volume. 
This percentage principle applies as well to a stand table. If made to include the trees 
tallied in estimating, the resultant table should show the distribution of diameters in 
the stand, on a percentage basis, regardless of whether all or only a portion of the 
trees in the stand are tallied. 

The total volume of the trees actually tallied in a stand table may be correlated with 
the volume of the forest or unit in one of two ways. 

By area. 1. The area covered by the trees tallied is known. This enables one to 
reduce the table to a stand per acre, which is assumed to be average for the forest. 

By voIuDte. 2. The volume tallied is taken as the basis. In this case, the average 
stand per acre tallied need not coincide with that of the forest. 

The relation in volume is found by comparing the total volume in the stand table 
with that of the forest. If 20 per cent has been tallied, the proportion is as i to 5. 
This is a more useful relation than area and more easily obtained. 

Purpose and Application, (c.) The real purpose of the stand table is to serve as a 
basis for determining the percentage of volume in the different diameters or age classes 
for the large area or working group which it represents. If a stand table can be 
divided into groups representing age classes, and the volumes in these age classes 
separated, these volumes can be expressed in terms of per cent of total volume for the 
stand table and if this table is properly constructed and representative of the forest, 
then these per cents will apply to the entire unit and will separate the total estimate 
into volume in the respective age classes. The steps then are: 

1. Separate the volume in the stand table into volumes of given age classes. 

2. Find the per cent of total volume which these age classes represent. 

3. Apply these per cents to the total estimate to divide the forest into age classes. 
159. Separation of Stand Table into Age Classes. The factors of the problem are: 

age of average tree of each age class, and its diameter, volume of said tree, number of 
trees in age class, in the stand table. When these factors are determined, the volume 
in the age class, its age and the area occupied can be determined and the results applied 
to the forest unit. 

In any method, only a feiv broad age classes slwiild be separated for the working group. 

By Diameter Groups. The simplest basis of division of the stand table is by diameter 
groups, assuming that the average age of a diameter class holds true for the trees in 
the class or will serve as a basis of volume separation (French method of 1883). 

But the division of mature or merchantable timber into age classes based on diameter 
alone, actually runs counter to a law of growth of trees growing in stands. Diameter 
growth of individual trees is far more variable than height growth, being afifected by 
the density of the stand and the origin and dominance of the individual tree. For trees 
of a given age class, whether growing in even-aged stands or scattered through older 
stands, the dominant trees grow more rapidly and reach larger ultimate sizes before 
death than do the intermediate, while the suppressed trees are much smaller in diameter 
for their age than the more vigorous trees. 

Trees of a given diameter over a large area include always a range of ages, and 
this range becomes greater as the diameter of the class increases.* 

By Age Groups. If as few as three broad groups are made (corresponding with the 



* In the larger diameter classes the range of age may again diminish due to the fact 
that only dominant trees reach these sizes. 



^54 



American rarest Reiriilation 



French sj'stem of two groups, plus a third overmature or decadent group), it may be 
possible to separate the stand on a basis of average age rather than diameter limits. 

For Western Yellow Pine, the young, merchantable age class, below the exploitable 
age. or up to 150 years in a 200 year rotation, may be tallied separately by the black 
color of bark and thus actually separated, as an age group, from the mature and veteran 
yellow pine timber. If this has not been done in general estimating, the stand table 
at least will have to show separate tallies for blackjack, and the per cent relation thus 
obtained is applied to the total estimate. 

Lacking this differentiation in appearance based on color of bark, the younger age 
class will probably have to be separated by diameter. It is in the determination of 
average age for the groups that a Haw appears (ignored by the French as immaterial). 

160. Average Age of Groups. To Determine Average Age of the Group. The process 
is identical with that described for determining the age of plots in constructing the 
yield table, 

1. Determine total volume in the diameter group. 

2. Get volume of average tree, 

3. From table of volumes on diameter for type, get diameter of this average tree. 

4. Look up age of said tree from growth curve based on diameter. 





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Fig. 



Volume of Western Yellow Pine, Distributed by Diameter Classes, Coconino National 

Forest. 

— Total Volume. 

— Volume of Mature Class, Decreasing by 5% for each 2-inch Diameter Class. 
Volume of Mature Class. Taking 507© of each Diameter Class. 

Division of Volumes into Mature and Veteran Classes, by Diameter Groups, 

each Containing an Eciual Volume. 



Figure 7 illustrates three different methods of dividing the stand or group into two 
age classes. The upper curve represents the volume actually occurring in each 
diameter class. 

By the first method, it is considered that the trees which belong to the veteran age 
class form an increasing per cent of each diameter class. This increase is taken for 
illustration as 5 per cent beginning with 14 inches. The resultant volume of the veterans 



Problem of Sustained Yield 



155 



is separated from that of the remaining mature age class by the line . This 

method was tried out on the Plumas National Forest in 1912, and described by 
Barrington Moore in Proceedings of Society of American Foresters, Vol. IX, No. 2, 
Page 216. 

This method uses diameter as a basis, but endeavors to follow the known laws of 
diameter growth by this cumbersome and impractical subdivision of each class. 

The second method makes an arbitrary division, based on diameter classes, between 

veterans and mature trees, and is illustrated by the vertical line . This is 

simple of application, but departs widely from the laws of growth, throwing many 
veterans in with the mature group, and vice versa. 

The third method is never used and is included only for purposes of comparison of 
results. It is to divide each diameter group into equal volumes for veterans and for 
mature, by the line . 

The resulting average tree, taken from the stand table on which these curves are 
based, for each of the three methods resulted as follows: 



Method used 
Diameter Classes Subdivided 

Two Diameter Groups 

Equal Volumes 





Volume of 


Diameter of 


Age of 




average tree 


average tree 


average tree 


Age class 


board feet 


inches 


■ years 


Veteran 


837 


27 


302 


Mature 


515 


23-5 


245 


Veteran 


1,267 


29-5 


345 


Mature 


393 


21.5 


214 


Veteran 


609 


24-S 


261 


Mature 


609 


24-5 


261 



These results indicate, first, that by the method of dividing by diameter groups, the 
average volume and diameter of the older group is raised arbitrarily by the exclusion 
of the slower growing smaller trees. When the average age is sought from a curve of 
diameter based on age, the indicated age is incorrect and exceeds the normal age of 
the group, so that it is necessary under these circumstances to derive age from a curve of 
age based directly on diameter. 

The reverse of this condition is shown by the purely theoretical division into groups 
of equal volume, by which the resulting average tree and age of each group is equal. 
The true average age and volume evidently lies between these extremes. While the 
crude basis of division adopted in the illustration is evidently incorrect in that it 
includes too great a portion of the total volume in the mature class and raises its age 
to 245 years, yet evidently this method comes close to a division in which volume and 
age of the average tree for each group correspond reasonably with the probable 
conditions whose determination is sought. 

This method is impractical in application, since the determination of the correct per 
cents of each diameter class to take for each age group is difficult, and the computation 
bunglesome. 

Based Directly on Age. But there is another and simpler way of solving this problem. 
The yield table is the best indication of the ages at which stands of the species approach 
maturity and begin to retrograde. The forest is composed of a series of age classes 
each including several diameters. When this continuous series is to be combined into 
but two groups, each group in turn embraces trees whose diameters overlap those in 
the other group. By shifting the average age of either group, the number of separate 
age classes included in both groups is changed, but there is no inherent difficulty in 
grouping the total number of age classes in any desired combination provided the two 
averages are far enough apart to fall within separate groups. 



156 America)! I'orcst kcgiilatioii 

It is possible, for instance, in a forest containing a definite number of trees, and a 
given total volume, to select two trees toi given volume, one for each of two broad 
groups. With these two volumes fixed, a definite number of trees will be required in 
each group to make up both the total volume and total number of trees in the forest. 

If falsely based on equal division of each diameter class, each group would take half 
the total, and the average volume of each group would be equal to that for the total 
stand. If based on division into 2 diameter groups the excess in normal size of the 
veterans would require too few trees in the class, the remainder required to make up 
the total being trees with the smaller average volume. 

To approximate the actual conditions in the forest, which is the result desired, let 
age be the starting point, since it is the basis sought. From the yield table select the 
age indicated as most characteristic of each class required. The steps then are: 

1. Age required for class. 

2. Diameter of a tree of this age. 

3. Average volume of a tree of this diameter. 

If the number of trees required for each age class, in order to make up both the total 
number and the total volume in the stand table, can now be found, the problem is 
solved. 

The solution given below can be applied only to two groups. In the example given 
Western Yellow Pine, the younger group has already been separated by the appearance 
of the bark. The method then will accomplish the separation of the mature or 
exploitable portion of the timber in a forest, above a given diameter, into the two 
groups representing decadent and vigorous trees. This is well worth doing. In forests 
already under management, in the second cutting cycle, the method will separate the 
mature from the young merchantable group. 

Formula. For this solution the full data for each separate diameter class in the stand 
table is not needed. A count of all trees tallied, and their total volume, will suffice. 
(It is assumed that Bfackjack are tallied separately.) 

Then 

x ^ number of mature trees. 

y = number of veteran trees. 

a = volume of an average mature tree. 

b = volume of an average veteran tree. 

Evidently ax -j- by ^ total volume of stand. 
But x-|-y= total number of trees in stand. 

If this total is multiplied by the volume of the average mature or smaller tree, a, the 
resultant volume a(x + y) can be subtracted from the total volume of the stand, to 
indicate the surplus over a(x + y) in the forest, due to the fact that a certain number 
of the trees actually have the average volume b instead of a. The surplus contained in 
one such tree is b — a or the difference in volume between a veteran and a mature tree. 
By dividing the total surplus by the surplus of one tree (b — a) the number of trees 
is found which must contain an average volume of h instead of a, and the remainder is 
the number of mature or a trees. 

Let c = total numl)er of trees 
d = total volume 

Then ax + by = d 

a(x + y) =ac 

(b — a)y ^ d — ac 

cl — ac 

b — a 
X ^ c — y 



Problem of Sustained Yield 157 

t6i. Illustration from Coconino National Forest. 

Stand Table 

Age class Trees Volume Per cent 

Blackjack 43,084 5.931 M 18 

Yellow Pine 44,423 27.042 M 82 



32,973 M 100 

Division of Yellow Pine into Veterans and Mature 

Diameter Volume per 

B.H. tree 

Age* inches** Ft. B.M.*** 

Veterans 300 27 805 

Mature 200 20.7 340 

Blackjack 90 17 ^37 

x = number of mature trees. 

y = number of veterans. 
340 X + 805 y = 27,042,800 ft. B. M. 
340 X + 340 y = 340 X 44423 or 15,103,820 ft. B. M. 
465 y = 11,938,780 ft. B. M. 

y=z 25,677 trees. 

x= 18,746 trees. 
Mature pine — 6,373.640 ft. B. M. 
Veterans =20,669,985 ft. B.M. 
Total =27,043,625 ft. B. M.* 

Percent of Mature Age Classes in Virgin Stands Only 
Timber above 12 inches D.B.H. 

In yellow pine. In total stand. 

Volume Volume 

Mature 23.6% i9-4% 

Veteran 76.4% 62.6% 

Blackjack .... 18.0% 

Total Stand of Sawtimber in Virgin Stands, Divided into Age Classes 
Veterans 1,972,618 M 

Mature 611,323 M 

Blackjack 567,206 M 



Total 3,151,147 M 

This gives us the volume in each of three age classes, corresponding to a definite 
average age. It is evident, by the method used, that should we decide to divide the 
stand into age classes based on an increased average age for veterans, the number of 
veteran trees in the forest would be reduced and of mature trees increased, which 
coincides with the laws of growth operating in the forest. The age groups are com- 
posite averages, and these averages may be altered by altering the basis, age, without 
introducing an error in fact or misinterpreting the true conditions of the stand. 

162. Immature Age Classes. In discussing the factor of the empirical yield table 



* Data from yield table. 

** Data from table. Diameter Growth, Bulletin loi (Page 20). T. S. Woolsey, Jr. 
*** Data from table. Volume on Diameter. 

* Error of 825 feet by neglecting decimals in obtaining volume per tree. 



158 American forest Regulation 

(§ 139). or actual density of the forest, it was shown that age and volume of the 
separate age classes in a forest must first be found, for owing to the difference which the 
age of a stand makes in its normal volume, no possible comparison with actual volume 
or estimated stand in a forest can be attempted without age as a basis. By the above 
method, the age of three classes, all that are needed, has been found. 

But before determining the density factor and empirical yield table (by the method 
described in § 141), a further analysis of the forest is necessary, to bi^mg out the 
importance of the role which reproduction and timber below merchantable sizes plays 
in any scheme of permanent regulation of yield. 

Effect on Density of Stand. The density of a given forest is determined by three 
factors; lirst. the age classes, themselves, as shown; second, the actual degree of 
stocking or occupation of the site by the merchantable stand compared to full stocking 
(to be determined); third, the proportion of the total area occupied by age classes 
below merchantable sizes. 

.A forest composed of trees and groups of all ages intermingled may have 50 per cent 
of its area occupied by merchantable timber. If the remaining 50 per cent is stocked 
with young or unmerchantable sizes the forest may have an actual density of 100 per 
cent. But unless it is possible to ascertain the area so stocked with young timber and 
deduct it, the 100 per cent stocking is not apparent in the mature stand. Thus the 
average stand per acre of merchantable timber of most forests is far below the stands on 
average acres of mature timber and should normallj^ be less than half of this figure. 
(See yield table for J/2 r years.) 

For computing the future yield of these mature classes, there are two alternatives, 
either to assume, e.g., that 100 per cent of the area is occupied by mature age classes, 
with a density of 50 per cent, a yield of J/2 the full yield per acre from the yield table, 
or else, to determine that but 50 per cent of the area is stocked with merchantable age 
classes but that the yield on this area will be 100 per cent of or equal to that of the 
yield table. In the even-aged form of forest the latter condition is evident. It is 
equally true of the many-aged form and should be so treated. The total future yield 
of these merchantable age classes will be the same in either case, but the average 
density of stocking is absolutely different. 

So much for the forest which is fully stocked. In the actual or partially stocked forest, 
the same relations exist. Assuming that one half of the area is reproduced to unmer- 
chantable, young ages, and that the merchantable timber, in quantity, by age classes, 
is but 60 per cent of a full yield; this merchantable timber may be considered as occupy- 
ing 30 per cent of the area with a yield 100 per cent of that of the yield table. And 
if the immature timber is disregarded, the mature stand if figured either way will give 
the same volume in future yield. Its actual volume and yield is not changed. Area 
and density are reciprocal factors. 

.50 X 60% ^= .30 X 100% of the standard yields. 

For regulation extending beyond the first cutting cycle, it is important to know 
what the immature age classes will yield. This yield will be largely determined, not 
by the number of seedlings established, but l)y the area restocked in acres. Yields 
are based on area, not on single trees. 

Effect on First Cutting, Cycle. If in the forest survey, this principle is recognized it 
will be possible to note the percentage of total area which is covered by young timber 
not under suppression, and having good chances for survival, just as separate areas are 
mapped in even-aged young stands. The more accurately this final result, i.e., the 
area ultimately stocked with timber by this reproduction, is predicted, the more accurate 
will be the prediction of the growth for the period when this young timber matures. 
On the other hand, quite a large error in this determination will not aflfect in any way 
the possible yields obtainable or predicted for the timber nozv of merchantable sices. 
What it will do is to give a false or erroneous idea of the possible total yield and con- 
sequent length of cutting cycle to be assigned during the rotation to this young timber, 
and hence to influence erroneously the length of the first cutting cycle required to remove the 
timber nozv mature. 



Proble>n of Sustained Yield 159 

Another reason in favor of determining the area restocked with young timber is 
this — if this area is subtracted before computing the density of stocking of the mature 
stands, this latter density tends to approach normal and be indicative of the actual 
yields per acre obtainable, while if not subtracted these yields are evidently much too low 
per acre. If the work is carefully done and the maximum area of young growth is 
secured and the stocking or reproduction is plentiful, the density factor obtained for 
the mature timber may be applied not merely to these mature stands, but to the young 
groivth as well, to assure a conservative prediction of future yields. 

These relations are illustrated below: 

Density of Stand, or Reduction Per Cent. To determine this average density or reduc- 
tion per cent, in the illustration, § 161, the area occupied by seedlings and saplings, 
i.e.. reproduction, and by poles, is to be first deducted from the net area, 438,423 
acres not yet cut over. 

Based on data obtained in the forest survey, the figure 25 per cent was adopted as 
representing the area within the working circle which is reproduced to seedlings and 
saplings; 25 per cent of 438,423 acres is 109,806 acres. The net area occupied by poles 
plus timber over 12 inches was then 328,617 acres. 

Poles, 6 to 12 inches in diameter, by data obtained from plots in normal or fully 
stocked stands averaged 88 poles per acre. On 7,034 acres tallied in preparing the 
stand table for the forest, the average number of poles 6 to 12 inches was 4.9. This 

gives ^'^ or 5.5 per cent of the total area stocked with poles at rate of 88 per acre, or 
88 

24.842 acres, leaving 303,775 acres net for timber over 12 inches. 

163. The Prediction of Actual or Empirical Yields for the Forest. Density of Stand, 

Timber 12" and Over. Applying the principle described in § 161 we get, for the 

merchantable timber, 









Acreage required 


Per cent 




Age 


Yield per acre 


if normally 


total net area, 


Class 


Years 


"Normal" ft. B.M. 


stocked (x) 


12" only 


Blackjack 


90 


9,400 


60,341 


31-3 


Mature 


200 


25,300 


24,163 


12.5 


Veterans 


300 


18,200 


108,385 


56.2 



Total "normally stocked" area 192,889 loo.o 

Then the density of mature age classes 12" and over is _y~-'_^" or 63.5 per cent. 

303.775 

Since the density of the timber above 12" is computed on the basis of 63.5 per cent 
of normal, it will be convenient to compute the density of the pole class 6" to 12" on 
the same basis instead of as normal density, since in the former case, the corrected 
empirical yield table can then be applied to all the age classes including poles and 
seedlings. Since the area of seedlings has been established on the basis of a stand 
which will produce a mature crop of average density, the assumption of the same 
density for seedlings is conservative, rather than "normal" density. 

By adding the normally stocked pole area, 24,842 acres, to the total actual area for 
timber 12" and over, the total actual area inclusive of poles is found, as 328,617 acres. 

But if poles are computed at 63.5 density, poles would occupy 39,121 acres instead of 
24,842 acres, giving an overlapping or siirplus area to adjust of 14,279 acres. 

Then ratio of density = 63.5 3^.6i7 + M.279 

328,617 

— 63.5 X 1.0422 or 66.2 (actually 66.18) 

Then .662 is the true density factor for the entire accessible area of yellow pine, the 

reduction per cent to apply to the yields given in the "normal" or standard yield table. 



(x) Found by dividing stand (§ 161) by yield of one acre "normal" from yield table 
for given age of stand. 



i6o 



.liiicricaii forest J'ici^ulatio)! 



If the area occupied by poles had been estimated on the basis of fully stocked stands 
correction would have been necessary as before to reduce poles to empirical density. 
Otherwise a "normal" yield per acre would be assumed for these classes at maturity. 
The above plan seems preferable. 

Area Occupied b\ Age Classes. From ratio (True ratio is 66.18, error 260 acres 

66.2 

adjusted.) 



Area of Age Classes 





"Normal" area 


Actual area 


Per cent of 


Age 


Class 


acres 


acres 


438,423 acres 


Years 


Poles 


24,842 


37,486 


8.5 


50 


Blackjack 


60,341 


91,072 


20.8 


100 


Mature 


24,163 


36,469 


8.3 


200 


Veterans 


108,385 


163,590 


37.4 


300 


Total 


217,731 


328,617 


75-0 




Reproduction 




1 09.806 


25.0 


20 



Total in forest working group 438,423 loo.o 

164. Application to Group Selection Forests. Relation of Cutting Cycle to 
Area Cut Over Already. Nothing illu.strates so well the interdependence of 
area and volume in regulation as the relation of the area already cut over, 
in a virgin forest, to the cutting cycle. 

Clear cut and ruined areas requiring restocking cannot be included in 
regulation for the first rotation at all. But areas cut by conservative methods, 
or areas in which restocking has taken place after former cuttings, are so 
included. 

To detern:inc the length of the first cutting cycle, which is "to complete 
the first cut of ^'irgin timber, the total area may be reduced by the area 
clear cut or destroyed, but on the area cut under conservative methods, it 
is better, if the process has not gone too far, to compute the proportion or 
per cent of the area whicli has been already cut as part of this first or transition 
cutting cycle, which has already elapsed. Where the cycle is ^ r and the 
per cent of the original stand cut is proportional to this cutting C3^cle, then 
each acre cut over in logging is equivalent to but ]/> an acre actually cut 
clear, but to one full superficial acre for the cutting cycle itself. An acre 
cut clear is equivalent not merely to one acre cut over in the first cycle, but, 
if reproduction and young timber are destroyed, to one acre in the second and 
subsequent cycles as well, which would thus liave their yields reduced. Hence 
the elimination of such areas in regulation during the first rotation. 



Illustration. Coconino. Areas: 

Virgin Timber 
Cut over 



438,423 acres 
116,137 acres 



Total 



554,560 acres 



Problem of Sustained Yield i6i 



Of the area cut over, there is 



Cut clear 45,473 acres 

Cut, leaving seed trees 8,208 

Cut by Forest Service marking rules 62,456 



Area conservatively cut 70,664 



Total 116,137 acres 

On the area of 70,664 acres, a second cut can be obtained in ^-2 r years. This is borne 
out, also by the per cent of area theoretically cut over as shown by the area of each 
age class in the remaining stand. 

An 80% cut will take, approximately 

Veterans ioo7o = 37-4% of acre 

Mature 90% = 7.5% 



Total 45% of area 

or nearly Yz. Then this area if Included as part of the unit, gives a total of 509,087 
acres, and an area cut over, in the first cycle, of 13.9 per cent equivalent to 14 years, 
on this reduced working circle. 

By including the clear cut area in a total of 554,560 acres, the per cent of area cut 
over for first cycle is 21 per cent or 21 years, and for the second cycle, 8 per cent or 
8 years, a total of 29 years cut, equivalent to 15 per cent of the total area. 

The total amount cut from the forest has been 593,621 M bd. ft. On the basis of 84 
bd. ft. mean annual growth on 554,560 acres, this is equivalent to 13 years' growth. 
The conclusion is, that a conservative reduction of 10 years can be made in the length 
of the first cutting cycle as having been already cut, and by reducing the area to 509,087 
acres, a period of 90 years should be allowed to complete the cut, with the assumption 
that 10 years' growth has taken place on the areas first cut over. 

For this cycle of 90 j^ears, the cut can be calculated based upon the actual age classes 
present, by volume, growth and area. 

165. Coordination of Cutting Cycle with Area and Volume of Existing Age Classes. 
There remains one problem in calculating growth. The progression or change repre- 
sented, on the one hand by growth, and on the other by cutting, when it extends over 
a period of 50 to 100 years affects the percentage of present or existing age classes cut, 
progressively. When the volume per cent cut, as 80 per cent, coincides with the volume 
of age classes, as veterans plus mature, it is best to assume, as do the French, that 
the cutting actually removes these classes completely. The volume left as seed trees 
in marking is balanced against an equal volume cut from a younger class. 

Then the cut for cc years will be the present volume plus J^ the growth of these 
classes, plus the volume of the timber falling, by age or size, in the period ^ cc 
below, with half its growth for cc years. To get the Yi growth over so long a period, it 
is better to take the yield of one acre at Y2 the cutting period than Y2 the difference in 
yield at beginning and end of period. The difference in results is shown below. 

Veterans, at 300 years = 12,050 ft. 

at 390 years = 1,600 ft. 

average = 6,825 ft. 

Yield at 345 years = 7,015 ft. 

Difference in yield, by second method, + 190 ft. per acre or 2.7%. 

The maturing class, since its age limits coincide with Y2 the cutting cycle, may be 
computed on the basis that the entire area of the next class covering cc years matures, 



l62 



Anicricaji Forest Regulation 



Yi is cut, and the average age of the stands cut is the present age plus Vi of the cutting 
cycle, thus giving J4 the "growth" on the total maturing stand. 

But when the first cut takes only a part of an age class, say 90 per cent of the mature 
timber class, it is a question as to whether we shall assume that the 10 per cent remain- 
ing shall be carried through to the end of the cutting cycle — which it would not be in 
practice — or our basis of calculation revised during the period to conform with the" 
actual practice of marking. 

The best plan is probably to add the 10 per cent of mature timber to the area of the 
residual growing stock where it belongs, and then in turn to deduct an equal area from 
the maturing Blackjack class which usually constitutes the residual growing stock, to 
be held over for the following cutting cycle, instead of figuring the entire class as 
entering the exploitable age class in this cycle. This is the same principle as raising 
the diameter limit (§ I44). 

On this basis the cut for the first 90 years will be. 

Exploitable class: 











Per cent of 










Average age 


Yield per 


total area 






Age class 


Age 


when cut 


acre. ft. 


to be cut 


Area, acres 


Total cut 


Veterans 


300 


345 


7.015 


100 


163,590 


1,147,583 M 


Mature 


200 


245 


17,610 


90 


32,823 


578,013 M 




1,725,596 M 


Maturing 


crop: 


Average age 


Yield per 
acre, bd. ft. 


Per cent of 
total area 








Age 


when cut 


when cut 


to be cut 


Area, acres 


Total cut 


Mature 


200 


24s 


17,600 


10 


3,646 


64.206 M 


Blackjack 


100 


145 


12,045 


96* 


87,423 


1,053.010 M 



1,127.216 M 



H cut = 563,608 M 

Total cut for cutting cycle 
Annual cut for 90 j^ears 



2,289,204 M bd. ft. 
25,435 M bd. ft. 



166. Comparison of Annual Cut by Methods of Regulation Proposed. A 

comparison of results may now be made, for the different methods of regu- 
lation proposed. 

Accepting a 100 year cutting cycle reduced to 90 years by previous cutting, 
for the removal of the first or original growth, and a cut of 80 per cent of 
the merchantable stand above 12 inches, as scaled in board feet, Scribner's 
Dec. C. Rule, we get, for a growing stock of 3,151,147 M ft.: 
By French method of 1883, 
80 X Ga 



Annual cut = '^^ ^^ """ ^ 28,054 M. This assumes a balance of growth 
90 
and decadence. 

By Von Mantel's formula, 
Annual cut = ^' ==31,511 M. This result must be rejected as based 
on false assumptions of normality. 



*9i,072 — 3,646 acres = 4 per cent of the Blackjack area, equivalent to 10 per cent of 
the smaller area of mature timber. 



Problem of Sustained Yield 163 

By cutting the mean empirical annual growth, 

Annual cut = 84 bd. ft. X 509,087 acres — 42,763 M. This fails to rec- 
ognize the presence of overmature, stagnant surplus. 

By Austrian formula, 

building up the stock to 3,525,427 M in 90 years. 
Annual cut = 38,605 M. 

By cutting the actual volume, plus growth, to 80 per cent and creating a 
felling reserve, 

Annual cut = 25,435 M, 

The agreement between the latter figure and the first, based on the original 
French method of 1883 which ignores growth and a felling reserve, and the 
difference of 13,170 M ft. in the annual cut as indicated by the Austrian 
formula are very significant, for upon these data rest the proof of the fact 
that the Austrian formula is not applicable to virgin forests in America if 
sustained yield is sought. Theoretically, the cut by this formula is nearly 
50 per cent higher than it should be by the best analysis of facts that we can 
get. This won't do. Evidently Munger's assumption of a balance between 
growth and decadence, and the original French plan of ignoring growth 
gives results much closer to the facts. The explanation lies in the fact that 
the Austrian formula assumes that the forest is already under regulation and 
is producing an annual increment on all stands. It does not take into account 
the natural loss from decadence, which must be incurred previous to cutting, 
on all stands, and in a long cutting cycle is a serious factor. 

In the present instance, the loss on 163,590 acres of veteran timber is the 
difference between the yield of one acre at 300 and 345 years, or half the 
period, multiplied by the area. This is, 

12,050 — 7,015 = 5,035 bd. ft. per acre 
5035 X 163,590 = 823,675 M bd. ft. in 90 years 
This represents a loss of 9,152 M ft. per year. Added to the indicated cut, 
by the last method, it would total 34,587 M bd. ft. or but 4,018 M bd. ft. per 
year less than the cut indicated by the Austrian formula. The formula fails 
because it is not based on actual conditions. The simple formula used by 
Munger is approximately correct because it does coincide with actual condi- 
tions. What is needed is a method by which the actual conditions and not 
formula determine the cut. The method proposed, whether it is applied by 
means of diameter classes and growth as in many-aged forests, or age classes, 
as in the above illustration, is based on the conditions in the forest, and makes 
no erroneous assumptions as to either form or arrangement of age classes, 
or growth. In this illustration, the growth reaching maturity in the 90 year 
period fails to balance the decadence or loss by 78,030 M bd. ft. or 867 M bd. ft. 
per year. In a forest composed largely of younger timber the reverse would 
be true. 

167. Summary of Basic Principles. To sum up: 

The basis of applied regulation in America as elsewhere must be the deter- 
mination of growth in the forest, for the average empirical stocking, and the 



164 Amcrica)i Forest Regulation 

division of the forest into age classes by volume and area either by diameter 
classes or directly on age. 

With a long cutting cycle and correspondingly large felling reserve required 
by our economic conditions of transition from virgin to regulated areas, 
the annual cut during the cutting cycle will be found by dividing by cc years 
the sum of: 

1. The volume 7wzv exploitable plus J 2 the growth during the cycle — best 
computed as, the volume which the exploitable timber will have in jA cc years, 

2. Plus y^ the present volume of the timber which will mature within the 
cycle, increased by j/^ of the growth on the volume cut, which is ^ of the 
growth on this total volume. 

The felling reserve will be the volume, at end of cutting cycle, of all stands 
which have matured within the cycle^ on areas after cutting is past on the 
area. This will be equivalent to tiie volume, at end of cycle, of stands now 
ranging in age from r — cc to r — 2 cc years. This basis is applicable to all 
forms of forest whether even- or many-aged. 

The analysis of the forest into age classes, the determination of the 
immature age classes by area and the obtaining of an empirical yield table 
will make possible the further regulation of the cut covering the second 
cutting cycle and remainder of the rotation. 

The balancing of the cut between the first and second cutting cycle, as far 
as permitted by silvicultural conditions, means carrying over the surplus, 
and can be accomplished by reducing the per cent of cut in first cutting, 
equivalent to raising the diameter limit and age, or vice versa. 

168. Factors Indicating a Shortening of the Cutting Cycle. Illustrations. 
The loss by decadence of 25 per cent of the total available timber, or 36 per 
cent of the cut actually realized, as shown above, is sufficiently serious to 
raise a question as to whether the cutting cycle in virgin forest should be 
prolonged to ^ r even if the per cent of the stand which must be cut indicates 
this procedure. The possibility of shortening the cycle, say to 3^ r. depends 
upon the data on growth obtained for cutover lands, and the reliability of 
conclusions drawn as to the behavior of the forest under management. 
Assuming, in the above case, that growth on cutover lands, per acre of tijnber, 
increases, from 84 bd. ft. to 105 bd. ft. per year, or 131 per cent, this would 
permit of shortening the cutting cycle to 80 years which at 103 bd. ft. per 
year would yield 8,400 bd. ft. as before. Then, if 10 years cut has already 
been made, a cutting cycle of 70 years would be indicated instead of 90 years. 
On this basis, the annual cut by the three methods discussed would be: 

1. By French Method, 

Annual cut ='^° ^^- = 36013 M. 
70 

2. By Austrian formula, 

Annual cut = 42,763 M -f 3151i47, M — 35254^7 M ^ 3-^16 M 

70 

3. By American Method, 
Annual cut ;= 34927 M. 



Problem of Sustained Yield 



165 



The latter figures are obtained as follows: 
I. Exploitable class. 



Age class 
Veterans 
Mature 



Average age Yield per 

Age when cut acre 

300 335 8,140 

200 335 18,105 



2. Maturing group. 



Average age Yield per 



Area 

163,590 
32,823 



Total cut 
1,331,622 M 
594,224 M 

1,925,846 M 





Age 


. when cut 


acre when cut 


Area 


Total cut 


Mature 


200 


235 


18,105 


3,646 


66,010 M 


Blackjack 


100 


135 


11,120 


87,423 


972,143 M 




1,038,153 M 




Yz to be cut 




519,076 








Total for 


cutting cycle 


2 


,444,922 M 






Annual cut 




34,927 M 





For this reduced cycle, the loss from decadence is 639,636 M bd. ft. or 3,9io bd. ft. per 
acre on 163.590 acres, giving a total, with the cut, of 3,084,458 M bd. ft. This loss is 
9.137 M bd. ft. per year — nearly the same annual loss as before, but less by 20 years, or 
by 174,039 M bd. ft. on account of the shortened cycle. The total cut is nearly the 
same being greater by 155,718 M for the shorter cycle. The real difiference lies in the 
more rapid cutting, giving an annual increase in the cut, of 9,492 M ft. or over 37 per 
cent. 

As this increased annual cut is justified only by a showing that growth on 
CHtover lands will permit the shortening of the cycle without interrupting 
the continuity of the yield, the importance of the point originally made, that 
growth studies on cutover land are the beginning of regulation, is again 
emphasized. Knowing the proper length of cycle, the disposal of the virgin 
timber even in the absence of data on decadence may usually be regulated 
on a conservative basis by ignoring both growth and decadence. 

169. Quiz. Why is sustained yield the ultimate problem? 
What are the limitations of the Austrian formula? Its good points? 
In many-aged stands how can yield tables be constructed? 
How can the yield table be applied to the forest? 

How can the stand table be separated into age classes and average age determined? 
How should immature age classes be treated? 
What must be done to secure "reduction per cent"? 
How is the area occupied by age classes secured? 

How is the cutting cycle coordinated with area and volume of existing age classes? 
Explain how the prediction of actual or empirical yields is done. 
In the case cited in § 166 which method indicates the largest yield? Why? 
Which two methods give similar results? Why? 
What are the basic principles of the American Method? 
With a long felling cycle how can the annual cut be calculated? 
What will the felling reserve be? 

Discuss the relative evils of loss through decadence as balanced by interruption of 
yield. 



CHAPTER XIII 

REGULATION OF FORESTS 
COMPOSED OF EVEN-AGED STANDS 

170. Relation of Cutting Cycle to Distribution of Age Classes in the 
Working Group. The same principles apply to the regulation of forests 
composed of even-aged stands, as to many-aged, or group selection forms. 
The method of cutting adopted will determine the future form of these 
forests. Clear cutting with artificial reproduction simply means a 100 per 
cent cut. and a cutting cycle equal to r years, unless modified by the inter- 
mixture of young stands on the general cutting area, forming several series 
of age classes as explained in § 116, when cutting cycles of less than r years 
are actually practiced. In this case, while each acre is cut but once in a 
rotation, the logging operations return to the logging unit to cut the succes- 
sively maturing stands at shorter intervals. If this were not so, at least 
during the first or transition rotation, these stands would reach ages ranging 
from r to 2 r years before they were all cut on the final logging unit. 

Just because a stand is even-aged now, it need not be clear cut. For 
instance in the Lodgepole pine forests on the Deerlodge National Forest, 
Montana and elsewhere, a long period of experimental cutting evolved a 
standard of marking which removed not 100 per cent but only 64 per cent 
of the stands which had reached exploitable size, leaving the other 36 per cent 
to put on growth. This process, continued, will break up the even age of 
these stands and bring on a group form. It will also increase* the yield per 
acre of large sized material and the total yield of wood. It introduces the 
factor of thinnings into the question of yields. 

171. Similarity of Problem with that of Many-aged Forms. The problem 
of regulating the even-aged form of forests should be approached in the same 
way as shown for many-aged forms. The first decision should be to deter- 
mine the length of the cutting cycle which is required to grow the second 
cut, basing this on the maturing of younger age classes. In even-aged stands 
the second cut will include the remainder of the mature timber in the stands 
which have been cut over in the first cutting cycle (the 34 per cent in the 
illustration) ; plus the stands, now immature, which will reach maturity 
within the second cycle, and which, in this form of forest are on separate 
areas, where in the many-aged forest they are mixed with the mature timber. 

It will probably be impossible to return to cut again even for thinnings or 
improvement cuttings, in stands once cut over until all the remaining acces- 
sible exploitable stands of overmature growth have been cut over once. The 
limitations of logging, as expressed by the cutting cycle, will prevent it. 

172. Application to Eastern Mixed Hardwoods. For lack of analysis and 
separation of the forest into its respective age classes, the application of 



* Sul)ject to losses from windfall, etc., which will probably be excessive. T. S. W., Jr. 



Regulation of Even-Aged Sta)ids 167 

this system in Eastern hardwoods at present is being based on the assumption 
that the forest can be divided into even-aged stands, w^hich will be clear cut. 
Areas are classed or allotted according as their average age is veteran, mature, 
or young merchantable. The periods favored in the Appalachian forests are 
20 years in length. The stands in the oldest class are roughly assumed to 
be cut clean, and to furnish the annual cut for the next period. (See data 
on Harvard Forest in appendix B.) The amount of the annual cut is based 
on the first plan proposed, corresponding with the French System' of 1883 
by neglecting both growth and decadence. 

Regulation on this basis is by the allotment principle. The areas regulated 
are small and the period of 20 years may not coincide with the cutting cycle, 
which may be much less, in case transportation is well organized. Or the 
forest may be composed of such large and irregular blocks of different age 
on account of past cuttings that no regular cutting cycle or felling series 
can possibly be hoped for in this rotation. If, for instance, all the over-mature 
timber in a working group were located on one logging unit, and it was 
decided to remove it in 20 years, the cutting within this period would not 
touch the remainder of the logging units. If each of the remaining logging 
units were also comparatively even-aged so that the major logging operations 
were concentrated in them successively, during the entire rotation, then the 
cutting cycle as far as there can be said to be one, is coincident with the 
rotation. The creation of such large areas of forest composed of a single age 
group is one of the evil results of our unavoidable former system of extensive 
logging operations conducted without thought for the future of the forest 
as a productive property. One of the main objects of regulation on such 
culled and mangled forests should be to plan as soon as possible for the 
adoption of a cutting cycle of reasonable shortness, which will permit of 
logging in every unit once during the cycle, and will thus create a number 
of series of age classes in each unit instead of one or two only. 

Just as, in the West, a cycle of ^ to j^ r may be forced on us by inaccessi- 
bility (and the necessity for extensive railroad logging operations), thus 
reducing the component age groups on any one area to 2 or 3, so the unreg- 
ulated exploitation of private areas has done the same thing in part on the 
Eastern forests which the government is now about to attempt to put under 
regulation for sustained yield. If we stop with the assumption that 
even when stands are in reality composed of several ages, we must, for the 
sake of simplicity, assume them to be of even age and, because it is apparently 
difficult to know how to calculate the possible cut under a system of partial 
cutting, we assume that the cut will be clear, then the outward form or model 
of our regulation will tend, not towards the actual creation of these several 
age series in each unit, but towards their further elimination ; either that or 
else there will be no real coordination between the calculated cut and cutting 
cycle, and the distribution of this cut by area and b}^ per cent of the stands 
taken. 

The argument here is not against the adoption of some plan of regulating 
the annual cut, which should be done on whatever basis is possible, pending 
the determination of the true condition of the age classes in the forest. It 



i68 America)! Forest Regulation 

is merely intended to point out the tendency to adopt the simplest conception 
of regulation, that of a single series of even-aged stands with cc = r, when 
possibly a little more study of the data at hand would perr^it of a basis more 
in harmony with the true state of the forest, and with the ultimate form 
required for best silvicultural results. If Appalachian hardwood forests are 
to be transposed by clear cutting into even-aged stands, the assumption of 
even-aged groups now tends in the right direction — but cz'cn then, the failure 
to recognize more than one of these groups to a logging unit tends to uselessly 
perpetuate the large cutting area which characterizes the long cutting cycle. 
An analysis of the forest into 2, 3 or 4 age classes on each logging unit is a 
great improvement over the neglect of these subdivisions by the process of 
lumping ofT the age of the whole unit. 

Any plan of regulation is better than none — but the initial plan, adopted 
admittedly in the absence of sufficient data, should as soon as possible give 
way to a plan based on accurate knowledge. Sometimes this additional data 
may be expensive to secure — but in the experience of the writer this is seldom 
the case provided the object or character of the data needed is understood, 
and the methods of securing it are well thought out. The expense of pre- 
paring the yield table, stand table and growth data for the Coconino Yellow 
Pine working plan was trivial compared with the value of the information 
secured. 

173. Prediction of Yields of Mixed Hardwoods. As long as investigators 
are tied to the fetish of mathematical accuracy in the interpretation of the 
play of living forces, whose results can only be mathematically ascertained 
after they have occurred, just so long will we be forced to the other extreme 
of adopting grossly inaccurate makeshifts in regulation of yield for lack of 
data of approximate accuracy which can be obtained and will vastly increase 
the certainty of our predictions, and management. The prediction of yield 
in mixed hardwood forests has for many years been considered an insoluble 
problem. No problem is insoluble provided the methods used are in harmony 
with the known laws governing the growth of the forests under investigation, 
and provided the allowable margin of error is not set so small as to be entirely 
out of harmony with the purposes of the prediction. All predictions of 
growth for long periods are subject to correction based on actual growth 
(see Gurnaud method § 83) after shorter periods have elapsed, hence why 
insist that they must be correct in the first place or else unserviceable? A 
little common sense is needed in tackling the problems of predicting growth 
in mixed forests. 

This is a discussion of regulation, not of growth studies — yet there can 
be no permanent regulation without growth studies. Where several species 
exist together, they may grow at different rates. What is needed for regu- 
lation is the total net growth on an acre in board feet or other units (cubic 
feet would be more desirable as a permanent basis) — not the growth of each 
separate species. It is necessary to know something of the relation of these 
species to each other, their survival and dominance and the per cent of each 
in the average stand to get closer to the total production per acre, but the 
stand table shows this composition of the stand, and the growth study shouUl 



Regulation of Evcn-Agcd Stands 169 

be based on silviculttiral knowledge of relations of species. Composite yield 
tables while lacking the apparent reliability and superficial accuracy of those 
made for pure stands are perfectly practical for the present when based on 
site qualities, and described as to average contents. Undoubtedly the best 
plan is to obtain yields per acre rather than to depend upon growth of individ- 
ual trees in diameter as described for many-aged forests, since the former 
method is based on results of growth on an area basis, while the latter takes 
no account of forces outside the individual tree measured, hence fails to 
record the loss or suppression in the stand (and losses through competition 
between species). 

174. Correlation of Regulation with Methods Proposed. Assuming that 
a standard "cove type" yield table has been constructed \vhich gives the 
relative yields per acre of this type at different ages, the problem of regulation 
consists, 

(a.) In separating the forest into component age classes, 

(b.) In determining the reduction per cent to apply to these age classes 
in order to predict the yield with the aid of the yield table. 

For the present the whole question of growth and future regulation is 
postponed by assuming the allotment plan with no growth, for cutting the 
mature timber. 

The measures which are possible are : 

1. An estimate, by area, of the young timber, either by maps, or by per 
cents, in as many age groups as is feasible or necessary, discounting for 
suppression to get net area of survival as nearly as possible. 

2. Separation of net remaining area of mature timber into 2 or 3 age 
classes based on : 

(a.) Mapped areas, where the form of forest permits it and average 
age can be obtained for each area. 

(b.) Diameter groups, when the first method is impossible; and cor- 
relation of age of these groups with age in the yield table by use of the 
tree of average diameter in each case, or, 

(c.) Further impro\ement on b by substituting the age of the average 
tree and its volume as a means of dividing the stand into 2 age groups as 
described in § 160. In applying this principle to mixed forests, the same 
method by which the average ages of plots for the yield table was determined 
may be used to get the age of the tree of average volume in the forest. 

The one requisite needed for the application of any of the methods depen- 
dent on the average tree for age, is a curve of growth based on diameter, 
which can be accepted as an average or representative curve for the type, 
and mixture. It will be said that with several species this is impossible. 
The answer is again that absolute mathematical accuracy is impossible for 
any method of determining an average unless all the elements are measured. 
An average, in forest mensuration, is used to avoid the need of complete 
measurements, and is not the result of total measurements. An average 
growth rate for several species does not presuppose that every tree in the 
forest must be measured for growth to insure correctness. If curves or 
growth showing age based on diameter for several species are weighted by 



lyo American Forest Regulation 

the average per cent of species in the type as shown by the stand table, the 
resultant curve will suffice for the purposes intended. Always bear in mind 
that forest mensuration is not exact mathematics; judgment in the use of 
the figures must decide the final answer. 

Growth studies, either in the original stand or on cutover land, must 
depend as much upon the stand table or growing stock, as upon the growth 
of the individual trees in the stand, hence the stand table is the first essential 
step in making any kind of a growth study of the forest as a whole, as dis- 
tinguished from standard plots or sample trees. It is the growth of the 
forest that we must have in order to regulate it, and it is the failure of our 
investigators to devise simple means of coordinating growth studies with 
the average stand in the forest which has discredited the utility of these 
growth studies and prevented their proper application. 

175. Coordination of Regulation with the Silvicultural Practice. Once the 
forest is separated into age classes by volume and area, it is no longer neces- 
sary to make false generalizations as to the per cent of each stand to cut. 
In the group selection type described under Western Yellow Pine, the per 
cent of the stand cut on the average acre can be coordinated easily with the 
age classes present and as these classes are mixed together, the assumption 
of a clear cut of each age class, or the removal of part of any age class and 
the reservation of the remainder as part of the residual growing stock, incurs 
no appreciable error in calculation. 

Where stands actually of even age are not cut clear but are culled, the 
initial problem of separating the areas of these stands and the calculation of 
growth is so simple that there is no reason why this growth data should 
not be coordinated with the actual silvicultural practice. 

176. Illustration for Lodgepole Pine. For example, if lodgepole pine should be cut 
on a rotation of 140 years, we need a yield table with reduction factor for the average 
stocking of the forest, and a table of areas, volumes, and ages of the age classes. The 
cutting cycle may then be fixed at say 40 years. This may be based on the fact that 
at least 70 per cent of the area is covered by timber below 100 years old, a satisfactory 
percentage of which will mature in this period. If timber approaching maturity is 
scarce, the cycle may be prolonged and vice versa. Due regard can be shown also to 
the necessity of carrying over a surplus of overmature timber, but this also is best 
attained by prolonging the cutting cycle rather than by raising the diameter limits or 
increasing the per cent of each stand to be left in the first cut — factors which are more 
or less fixed by silvicultural and logging conditions. 

Following the principles laid down for the transition cutting cycle (par. 138), the 
stands which will represent the cut in the first cycle will embrace all whose age is 
above r — cc years, or from 100 years up, including the surplus of over-mature timber. 
The growth on these stands is found by determining the yield which they will have in 
J4 cc years, or 20 years, by taking the yield for each age class, at the increased age 
thus fixed, from the yield table. But to successfully transform the forest, the minimum 
age of stands to be cut as the operations progress over the area must be set at 
r — y2 cc, or 120 years. 

To take a concrete case for Lodgepole pine on the Bernice working circle, Deerlodge 
National Forest,* where the rotation is 140 years: 



* Bulletin 234, U. S. Dept. of Agriculture, page 35; yield table, Bui. 154, U. S. Dept. 
of Agriculture, page 32. At 140 years, normal yield is 15,840 bd. ft. or 113 bd. ft., mean 
annual growth per acre. 



Regulation of Even-Aged Stands 



171 



Since the reduction factor on this forest was applied, in estimating, to each age 
class separately, tlie growth per acre can be predicted separately as well, for these age classes 
by using the correct reduction per cent for each age class. But to simplify the illus- 
tration an average factor will be adopted. 

On the basis of area stocked: i.e., stocking reduced to normal acres, which weighs 
equally all age classes, the density factor averages 49 per cent. But on the basis of 
comparative present volume which gives greatest weight to the older age classes, the 
density factor is but 33y3 per cent. The latter ratio will be adopted for the first two 
cutting cycles for this reason. The empirical yield table then becomes, 

Table 16. Yield Table for Bernice Division, Deerlodge National Forest. 
Lodgepole Pine. Reduction to 33^ per cent. 



Age 




Age 


Age 




Age 




Age 


Years 


Bd. ft. 


Years 


Bd. ft. Years 


Bd. ft. 


Years 


Bd. ft. 


Years Bd. ft. 


30 


180 


60 


1,620 90 


3,160 


120 


4,540 


150 5,640 


40 


640 


70 


2,140 100 


3,640 


130 


4,920 


160 5,960 


50 


1,120 


80 


2,680 no 


4,100 


140 


5,280 


170 6,240 


The areas in the working circle are: 










Age 




Area 


Present yield 


Age 




Area 


Present yield 


years 




acres 


M. bd. ft. 


years 




acres 


M. bd. ft. 


10 




1,570 




70 




1,928 


4,125 


20 




9,742 




80 




2,448 


6,560 


30 




5,511 


991 


90 




2,092 


6,620 


40 




7,559 


4,837 


100 




3,040 


4.985 


50 




1,412 


1,581 


no 




396 


1,623 


60 




4,887 


7,916 












70 




1,928 


4,125 


Total 




39,238 M 


80 


120 


2,448 
to 160 


6,560 

14,443 


j 










160 


to 200 


2,844 


y Total 




53. 


603 M 




over 200 
Total Acres 


474 


i 




92, 






58.346 


841 M 



The present volume in stands containing merchantable timber is 92,831 M bd. ft. of 
which 80 per cent is Lodgepole; therefore, growth can be based solely on Lodgepole 
without incurring too great an error. Of this, 53,603 M bd. ft. is in stands 120 years 
and over in age. 

Trial Calculation to Determine the Cutting Cycle. First Trial. The area now occupied 
by mature timber is 33 per cent of the total area stocked. On this basis, and to aid in 
establishing a cutting cycle approximately Ys r, the cycle will be first tested at 40 years. 
The per cent of cut will be 66 or two-thirds of the present stand. 

The minimum of exploitable age will be set at r — ^ cc or 120 years. 

The cut for the first 40-year cycle will be but 66 per cent of each stand leaving 34 
per cent for the next cycle. This is approximated as the average per cent to leave. 
The older stands will be cut more heavily, and the younger, more lightly. 

Growth in all stands is computed for 14 cc or 20 years. On the older stands, above 
120 years, an average of 37 board feet per year is calculated from the yield table and 
applied to all stands. This gives, on 17,761 acres, for 20 years, a total of 13,143 M 
board feet. 

A more accurate method can be applied, which will be illustrated in the case of the 
stands below 120 years. Since the volume and age of each stand is known and there- 
fore its relative density, the growth should be predicted directly on the existing stands. 



172 American Forest Regulation 

This can be done by determining the per cent of increase shown by the yield table for 
a 20-year period for each age class, and applying this per cent to the present volume. 

For iio-year class this is^^ — or 120 per cent. 
4100 

For IOC-year class it is'^'^^-or 124.7 pcr cent. 
3640 

The yield of these stands in 20 years is then, 

For iio-year class, 1,623 M plus 20 per cent or 1,947 M. 

For 100-year class, 4,985 M plus 24.7 per cent or 6,216 M. 



Total 8,163 M. 

The total volume to be cut within the 40-year cycle is, 

Volume of stands 120 years and older 53,603 M. 

Growth at 27 bd. ft. per acre annually 13, 143 M. 

Volume and growth in no and lOO-year stands 8,163 M. 



Total 74.909 M. 

66 per cent to be cut 49,439 M. 

Annual cut, i/40th 1,235 M. 

At the beginning of the second cycle, the 34 per cent left from these stands has 
already laid on an average of 20-years growth, and will lay on 20 years additional 
growth before cutting during this 40-year cycle. The growth of these thinned stands 
cannot be predicted with certainty, but such data as is available tend to show that the 
species has marked recuperation powers even to the age of 400 years. Hence it is fair 
to assume that on the remaining stand the growth will equal that laid on in the first 
cycle, or 27 bd. ft. per acre. 

For 40 years and on 21,197 acres, this equals 31.371 M bd. ft. 
Upon the residual stand of 25,470 M bd. ft. 



or a total of 66,841 M bd. ft. 

To this must be added the yield of stands now between 100 and 60 years of age, which 
will grow for 40 years in the first cycle and an average of 20 years during the second 
cycle before cutting. 

Using the same method of percentages as for the first cycle, these are. for 60 years' 
growth. 

For 90-vcar stands ^^° or 178 per cent. 
3160 

8o-vear stands ^~ or 197 per cent. 
2680 

70-year stands ^^ or 230 jicr cent. 
2140 

60-year stands —^ .or 280 per cent. 
T620 

The yields of these classes will then be, 

For 90-year stands at 150 years, 6,620 M, plus 78 per cent or 1 1,883 M. 

For 80-year stands at 140 years, 6,560 M, plus 97 per cent or 12,923 M. 

For 70-year stands at 130 years, 4.125 M, plus 130 per cent or 9.487 M. 

T"or Co-year stands at 120 years, 7.916 M, plus 180 per cent or 22.164 IM. 

Total 56.457 M. 



Regulation of Even-Aged Sta}ids 173 

If 66 per cent of these stands is cut as before, this gives a cut of 37,261 M. 

This, with the older thinned stands gives a total cut of 104,102 M. 

and an annual cut of 1/40, or 2,605 M. 

Thus by the plan of cutting but Ys of each stand now, at a sacrifice of 637 M bd. ft. 
per year of the possible cut, it appears that the probable cut in the next cycle will be 
more than doubled. If the stands are cut clean the respective cuts will be, 

For the first cycle 74.909 M. 

annual cut 1,872 M. 

For the second cycle 56,457 M. 

annual cut 1.411 M. 

Total for both cycles 131,366 M. 

Total, if Vs is cut i53,54i M, 

plus a reserve, in this case of 19,196 M or a total gain in production by the second 
method of 41,371 M in 80 years or 517 M per year, which is about 32 per cent of the 
average 80-year cuts of 1,642 M by the first or clear cutting method. In effect, such a 
system is equivalent to lengthening the rotation by at least 20 years. 

These figures are given to illustrate the method by which different cutting cycles and 
rotations may be tested, to determine the actual yields and to decide upon the proper 
factors to use in regulation. They serve also to bring out the enormous influence of 
growth upon the volume of the possible cut. 

If the discrepancy between the predicted cut for the first two cycles appears too 
great, the cut for the first cycle can be increased, and made more nearly equal with the 
second, by shortening this cycle and removing the surplus of timber above the age of 
140 years in a shorter period. It is suggested that the student perform one or more of 
these calculations by the methods indicated. 

177. Summary of Principles for American Regulation. The European 
allotment principle attains progress towards regulation by transferring stands 
whose age classifies them with a given fixed period, into an earlier or later 
period for cutting, thus equalizing the areas reproduced within the period 
by advancing or retarding the normal age of exploitation for specific stands. 

The periods are of fixed length, equal to a definite proportion of the rotation, 
and as the cutting cycle is usually yi to yi oi this short period, there is no 
difficulty in reaching and cutting any stand when needed. 

In America the cutting cycle or length of time elapsing between successive 
cuts is determined by transportation costs and frequently becomes the govern- 
ing principle of cutting and hence of regulation. 

The first principle of securing sustained yield in America is therefore to 
determine the length of the first cutting cycle so as to fix the amount of the 
annual cut, on the basis of a determined cut per acre. As an aid in this deter- 
mination, the growth on cutover lands, in selection or group cuttings, and 
the growth on cutover lands plus the young stands which mature, in even- 
aged forests, will be measured to indicate the annual cut possible in the 
second cycle. 

The annual cut in the two cycles can best be equalized by lengthening or 
shortening the first cutting cycle, the former reducing the cut in the first cycle 
and increasing it in the second, and vice versa. 

Where more than two cycles are apportioned to a rotation, the per cent 
of the rotation assigned to the remaining cycles may be made proportional 
to the per cent of. the area of the working circle, occupied by timber whose 



174 American Forest Regulation 

age classes it with these cycles. The first two cycles can usually include 
all the timber now merchantable . 

The working out of this principle is well illustrated by the above case, 
and as set forth it constitutes what has been termed the "American" method 
of regulation whose characteristics are, determination and equalization of 
the annual cut on basis of volume, by means of varying the length of the first 
and second cutting cycles, and determination of the actual annual cut by using 
the principle of a felling reserve and cutting series with a minimum exploitable 
age of r — ^ cc years and an allotment of areas or stands for cutting within 
the period, down to and including r — cc years. Just to the extent that the 
per cent of the stand per acre, in many-aged forests, or the per cent of the 
total area of a logging unit, in even-aged stands, which must be cut, can 
be reduced because of increased accessibility and better transportation condi- 
tions, does the cutting cycle lose its controlling force in regulation, and the 
need for basing regulation on length of this cycle, and upon the cutting series 
and felling reserve which is created by it, diminishes, until with short cycles 
of 5 to 8 years and perfect transportation, the allotment principle of regulation 
may be applied without regard to the cutting cycle. But these conditions 
are for the future in many sections of the West, and the principles above 
described will be applied in cutting whether or not they are recognized as 
they should be in regulation. 

178. Quiz. Can these principles be applied to even-aged stands? or to Eastern 
mixed hardwoods? 

How could the mixed hardwoods of the Southern Appalachians be regulated under 
present conditions? 

Why must regulation be coordinated with silvicultural practice? 

How can the annual cut in two cutting cycles be best equalized? 

Why is this better than an allotment of areas for cutting within a definite period? 

When should an allotment method be used? 



APPENDIX 

CONTENTS 

A. (a) Forest Management in Nine European States (from Martin), page 175. 
(b) Financial Rotations (from Endres), page 200. 

B. Growing Stock and Yield, Harvard Forest, page 204. 

C. Example of a Preliminary Policy Statement for Inyo National Forest, page 205. 

D. Results of Forest Management in Savoie, France, page 208. 

E. Examples of Yield Calculations from National Forest Management Plans, 1921, 

page 210. 

F. Comment on Wolff Formula, page 212. 

APPENDIX A. (a) FOREST MANAGEMENT IN NINE EUROPEAN STATES. 

The data on European management is a free and condensed and not a literal trans- 
lation of the third edition of H. Martin's Forsteinrichtung. The wording has frequently 
been simplified but without changing the real meaning nor diminishing the value of 
the original text. The synonyms management plan, and working plan have been freely 
varied. In some instances considerable liberty has been taken in completely rearrang- 
ing the text. But in adhering to a translation at all, the "English" has had to be sacri- 
ficed to a considerable extent. The use of brackets to simplify some of the involved 
and complex German sentences perhaps has been carried to extremes but seems 
necessary to make the text understandable. 

The following countries are included: (i) Prussia, (2) Bavaria, (3) Kingdom of 
Saxonj"-, (4) Wiirtemberg, (5) Baden, (6) Grand Duchy of Hesse, (7) Grand Duchy of 
Saxony, (8) Alsace-Lorraine, (9) Austria. Martin's comment on French regulation 
has been omitted since this is discussed in great detail in the text and in the Appendix 
of "Studies in French Forestry." Accepted principles proven by these discussions have 
been embodied in the main text of this book. 

I. PRUSSIA. (Page 223)* 

During the nineteenth century the allotment method was the dominant method of 
regulating the yield in Prussia. It came into use through G. L. Hartig, in the form 
of the strict volume allotment (Massenfachwerk). According to the Instructions of 
1819 the yield was to be shown for all periods of the 120 year rotation (or period of 
organization), separated into main and preliminary yield, divided into classes (timber, 
split fuelwood, round billets, brushwood). This method of Hartig's on account of the 
"circumstantiality" of the calculations (for which a satisfactory basis was lacking), 
could not long be maintained. The elaboration of working plans progressed too slowly. 
Therefore new instructions were issued in the year 1836 by Oberlandforstmeister von 



* Figures in brackets denote the page in Martin's Forsteinrichtung, third edition, and 
thus facilitate reference to the original text. 

Mrs. Fernow, who kindly read the translation to Dr. Fernow, writes that Dr. Fernow 
.... "thinks you have generally improved on Martin, whose style is certainly most 
cumbrous" .... It should be noted that "abtheilung" means lot when "jagen" 
signifies compartment, but lot is usually the translation of "unterabtheilung" when the 
compartment is denoted by the German word "abtheilung." 

An excellent way of mastering the variations and similarities of regulation in the 
foregoing states is to read through the translation subject by subject as well as country 
by country. For example take the subject of allotment by periods and it is instructive 
to find that all states have usually abandoned the cumbrous and methodical scheme of 
actually alloting stands to periods 40, and 60 years hence. 



176 American forest Regulation 

Reuss, after summary yield determinations for the State forests had been carried on in 
the years 1826 to 1835; these instructions continued to be used almost to the end of 
the nineteenth century; to be sure, they are also based on volume-allotment but they 
simplified the yield calculations and took area into consideration. At the same time 
attention was paid to a proper distribution of age classes and regulation of a felling 
series. In harmony with these instructions for the elaboration of working plans, two 
different kinds of allotment came into use according to the stand conditions in each 
case: 

(a) The combined allotment (Fachwerk) which was preferably to be applied to 
irregular stands. 

(b) The area allotment (Flaechenfacliwerk) which under regular conditions was 
considered sufficient. Usually only simple areas formed the basis. 

In recent times the yield calculations were limited more and more to the first period 
and the allotment for later periods zms often entirely omitted. In other directions simplili- 
cations were also introduced. The most important essential prescriptions of the method 
in present use are as follows: 

1. Prescriptions for the Elaboration of New Working Plans, (i) Preliminary Dis- 
cussion. Before beginning the work of regulation preliminary discussion takes place 
between the district forester, inspector and supervisor, in which (on the basis of the 
detailed results of the former management), propositions for the future management 
are laid down. This discussion is centered on: the system of roads and division lines, 
the boundaries, maps and survey, the condition of the forest, the previous and future 
management, and the method to be followed in the organization of working i)lans. 

2. Administrative Subdivision; (a) Working Groups and Management Classes. The 
formation of working groups is a special peculiarity of the Prussian State Forest 
management. Already in the instructions of Frederick the Great this is prescribed. 
To justify the formation of groups it is stated: "Partly the size of the forests united 
into one supervisorship and partly differences in portions of these forests as regards 
methods of management, condition of stands, market, or servitudes, make it desirable 
or necessary not only to regulate the cut for sustained yield for the Forest as a whole, 
but to divide it into more or less independent organic parts of the whole forest forming 
main management units or groups, within which the sustained yield management can 
be either introduced immediately or at least prepared for by the establishment of 
ordered age classes." (P. 225) According to present practice each protection district 
forms a group. Such coppice forests that are to form a felling series by themselves, 
as well as coppice under standards and selection forests, for which a special working 
plan is to be made, are segregated as special working groups. 

Besides the division into groups, the formation of management classes is also insti- 
tuted in Prussia. The reasons for these are first of all to be found in the occurrence 
of the four groups of timber species on large areas (oak, beech and other hardwoods, 
softwoods, and conifers), and further in differences of management (especially as 
regards rotation). 

(b) Per}nancnt Subdivisions (H'irthscliaftsfiguren). The prescriptions given for the 
subdivision essentially agree with the rules given in the first section of the first part 
(of this volume), which are derived from Prussian practice. This subdivision into 
permanent subdivisions (Wirtschaftsfiguren), which are here called compartments 
(Jagen), is made by a network of straight lines, which cut each other as nearly as 
possible at right angles. The rides (Gestelle) are to be laid out from east to west and 
from south to north or parallel and perpendicular to an intersecting main road or 
railway. Where danger from wind is to be feared, the dividing lines are to be so 
laid that they form an angle of 45 degrees towards the most dangerous wind direction. 

In mountain forests the division is to be made on the basis of the network of roads. 
"The roads are to form the shortest possible connection to market or to means of 
communication with the market; they are to be planned in relation to each other, to 
cross mountains over passes and to be located so as to be easily built. The grade 



Appendix i77 

is not to exceed 6% except when thereby a specially favorable location of the roads 
can be secured." 

The shape of the management units is to be as regular as possible without acute 
angles, so far as possible facing in one direction and bounded or intersected by roads 
in such a manner that all the wood cut in them can be readily moved to the highways. 
If the boundaries are not formed by roads, either natural boundaries should be relied 
upon or cultural limits, railroads or rides (Schneisen, which as far as possible are located 
in the direction of the steepest grade). 

The size of the permanent management units is to average 50 to 75 acres — in spruce 
25 to 62. The main rides of a compartment division, which run approximately from 
east to west, are marked with Roman (p. 226) capitals; the "fire-rides" which are 
perpendicular to these, are marked with small letters. The compartments in the plains 
are numbered from east to west, proceeding from south to north. In mountainous 
territory, sections of country of uniform character are combined into groups and 
numbered accordingly. 

(c) Stand Divisions. The differences in the stands to be found within the permanent 
compartments are segregated as lots (Abtheilungen and Unterabtheilungen). Com- 
partments are segregated, if the limits of the stand are likely to remain permanent and 
either coincide with rides, roads, watercourses, etc. or can be laid out on lines suitable 
for roads, which are then marked with posts and direction ditches. In all other cases, 
especially when the difference is to be obliterated in the course of the first period, a 
segregation as lots suffices, the boundaries of which are not indicated and marked 
locally. Severance fellings and safety lines are to be segregated as lots. Compart- 
ments are denoted by small Latin letters, the lots by the compartment letters with a 
small number (a\ a^). 

3. Site and Stand Survey, (a) Description and Valuation of Sites. For the geo- 
logical description of the soil and for its composition the geologic-agronomic maps of 
the Geological Survey on the scale of i to 25,000 are to be used. As regards termin- 
ology, that of the German Forest Experiment Stations is to be followed. The site 
class is to be estimated on the basis of the Experiment Station yield tables. The 
average height of the main stand, ascertained by a few measurements, serves as measure 
of the site value. 

(b) Description of Stand This is to be brief. Uniform stands of regular character 
are sufficiently described by stating the species, age, and the full yield. Striking 
defects of the stand are to be specially noted. In uneven-aged stands in which the 
age classes gradually merge into each other, the age limits and the average age are to 
be stated. If several age classes are strictly differentiated, the age of the classes is to 
be noted (p. 227). The degree of density is to be estimated specially for the different 
species. Their sum must coincide with the total density of the entire stand. 

4. Age Class Table. This table forms the most important numerical basis of the 
working plan in the timber forest; in it the stands are arranged according to sequence 
of the groups, compartments and lots. In mixed stands, and in those containing 
different age classes, the areas are divided according to the proportion of these dif- 
ferences. The area (to be determined by survey or estimate), which each species and 
each separately stated age class occupies (within a compartment or lot) is entered on 
a separate line. Thus it is possible where mixed stands predominate to record the 
species more correctly than can be done, if. in the table the whole area is assigned to 
the dominant species. The areas are compiled, separately according to the four species 
groups and, if several management classes are involved, also separately for these, by 
groups and in totals. 

If it appears desirable to record and compile the stands according to site class 
parcels, this may be done. On the basis of such data it is possible to calculate or 
estimate the actual and normal growing stock of the age classes and of the total forest. 

5. Regulating the Cut. (a) Standard of Measure. The measure for the amount 
of cut and tlie proof of sustained yield is the normal periodic area. This is determined 
for each management class according to the relation of the length of the period (=20 



178 American forest Regulation 

years) to the rotation. For the working groups it is not necessary to adhere to the 
normal felling area. With irregular age classes corresponding changes are made. The 
area of the first period is to be made smaller when there is a deficiency, — larger when a 
surplus of mature timber exists. Under difficult (cultural) conditions and especially 
when species with long regeneration periods are involved, the first and second periods 
are to have felling areas allotted. In cases where the sequence of cuts has special 
significance the progress of fellings is to be shown for a longer period. The felling 
areas of the first period are listed separately according to species, groups and manage- 
ment classes, group by group and for the whole forest. For the areas of latter periods 
and the segregation of stands according to species, groups and management classes 
are not required. 

(b) Choice of the Stands to be Regenerated (p. 22S). The correct choice of the stands 
of the present period of management is considered one of the most important tasks of 
organization. It is essential that the stands are utilized at time of maturity, that the 
most suitable felling series is established, the sustained yield assured, and the most 
suitable species regenerated. 

(f) Rotation. The (official) determination of the rotation for the main species is 
reserved for the Minister. The proposals for the length of the rotation are to be stated 
and argued in the preliminary proceedings. For a decision on the length of rotation, 
data are to be secured in suitable "reviers" (before the organization takes place) for 
the most important species and the most commonly occurring sites; the stumpage 
prices (free of logging cost) per cubic meter of timber for the most important age 
classes can thus be studied. 

6. Determination of Timber Volumes and Cut. (a) Main cut. The allotment of 
the cut (main and intermediate) is done according to the instructions for keeping the 
control book. The yield (main cut) is composed of the present volume plus the incre- 
ment for the next ten years. All volume data refer to timber and are separately listed 
according to the four species groups already mentioned. 

The determination of the volume of the first period is made by calipering all stems, 
unless a simpler method appears satisfactory. F'or the calculation of the volumes the 
volume tables of the German Forest Experiment Stations are as a rule to be used. 
The volume of the young regular stands is estimated by yield tables or ascertained by 
sarfiple plots. The increment percents are cited according to the yield tables; for open 
stands simple increment investigations are to be undertaken. The annual felling budget 
is then obtained by dividing the sum of the volumes assigned to the first period by 20 
(i.e. years in period). 

{b) Intermediate Cuts (p. 229). To furnish a definite basis for the execution of 
thinnings, a plan is elaborated in which the areas of the stands to be thinned or cleaned 
in the next decade — separated into those under and over 40 years — are enumerated. 
The division of these areas by ten gives the yearly thinning area. If the stands are 
to be thinned twice (or thrice) in one decade their area is added again (or three times). 
The exact year of the thinning is not dictated for each stand. 

The felling budget for the intermediate cut is estimated on the basis of the j'ields which 

the intermediate cuts have furnished on the average xn recent j-ears, excluding 

unusually high or low yields. The average is increased or decreased if the annual area 
to be thinned deviates considerably from the area annually thinned (in the years used 
for comparison) or if other reasons give occasion for it (especially changes in the 
thinning technique). 

7. Coppice and Selection Forest Organization, (a) Coppice. Extensive coppice 
forests are segregated as special working groups. Every group is to contain a number 
of annual felling areas corresponding to the rotation and with approximately equal 
areas. The felling areas are chosen according to their maturity and with regard to a 
satisfactory felling series. It is generally considered sufficient to determine in each 
group the number of felling areas and the year of their cutting, without locating the 
individual areas in the field or on the map. Lots are not segregated. 

The yields of timber and brush are to be estimated on the basis of former results. 



Appendix 179 

The annual cut is found by dividing the number of years of the rotation into the sum 
of the yield of all felling areas segregated by the species groups. 

(b) Selection Forest. The regulation of the cut is simple. A segregation of lots 
within the compartments is as a rule to be avoided. In the age class table the areas 
by species and age classes are to be estimated and stated separately. The ascertain- 
ment of the growing stock stem by stem is not necessary. All wood yield is to be 
booked as main cut. 

(P. 230) The cuts for each management unit of the first period are estimated from 
yield tables according to the maturity (of the parts) of the stand for the middle of the 
period, segregating (as usual) the four species groups; or are estimated by calipering. 
If the selection forest forms a special group the average increment for every manage- 
ment unit is estimated and the total increment revealed thereby is to be considered as 
prescribed cut (felling budget), in so far as the age group proportion does not reveal a 
lack or excess of growing stock, or the character of the stands does not necessitate a 
greater or reduced cut. 

Wherever the selection forest has been in existence for a considerable time the future 
prescribed cut may be deduced from a consideration of the changes in the age group 
relations consequent upon the application of the previous felling budget. For a check 
on the progress of fellings a return period of ten years is as a rule established. 

II. Control and Development of Working Plans. A. Control. For control of the 
management and for the development of the working plan there is: (i) the Control 
book. (2) the Ledger, and (3) the Area Register. 

(i) The Control Book serves as a check on the estimates and fellings, and consists 
of three parts. 

The first part (A) contains for every permanent stand a special record in which are 
entered annually, all fellings divided into main and intermediate, with the amount of 
the material realized. The main cut includes those cuts of the main stand which either 
produce an entire renewal of the stand or such a culling as to necessitate its entire 
renewal or filling in, or if there is a considerable diminution of the main yield as 
determined by the stock taking. The intermediate cut includes: (a) thinnings in the 
lower story; (b) fellings of single stems and groups carried out for the benefit of the 
main stand, which do not necessitate a renewal of the stand and (p. 231) which do not 
exceed 5% of the prescribed main yield (cleanings, improvement cuttings); (c) fellings 
which take place in consequence of injuries to the forest without, however, necessitating 
restocking, and without diminishing the prescribed main felling by more than 5%. 
Fellings from (a) to (c) which take place in stands of the current working period, are 
to be considered as main fellings. 

All yields of the coppice under standards and selection forest are also reckoned as 
main fellings. When the cut prescribed by the working plan (in the main felling of 
the timber forest) is completed, the realized yields of timber are summed up and 
transferred to the second part (Ai) (see page 180) and here compared with the estimated 
yields. The intermediate yields are excluded from this transfer as is also the root 
and brush-wood. Every three years the part Ai is balanced; it is then calculated 
whether the stand divisions (re final cut) during these three years have yielded more 
or less than the estimated yield and what amount of wood above the estimate may be 
utilized or how much the felling budget must be reduced (to make up for a deficit). 

The third part (d) contains the annual comparison of the cut in timber with the 
estimated amount, taking into consideration the changes demanded by the results of 
part Ai. Excess or deficit in one year's fellings (as compared with the felling budget) 
is used for the determination of the usable volume of fellings added or subtracted from 
the felling budget. The result (the remainder or the sum) constitutes the standard for 
the following economic year; the permissible cut (in the main felling) may only be 
exceeded by 10% at the highest, without Ministerial permission. No limitation exists 
in this direction for intermediate returns; they are controlled only by area (and 
silvicultural practice). 

2. The Ledger (Hauptmerkbuch). This aims (in conjunction with the Control 



i8o America)! Forest Regulation 

Book and the Area Register) at furnishing the leases for the control, proving and 
(p. 232) correction of the forest management. "It is to form a history of the Revier, 
which enables one to see the development and changes of conditions in the whole 
Revier as well as in its integral parts, and furnishes to the succeeding administrator 
a knowledge of events influencing the management, the measures adopted, the work 
performed, the observations and experiences had, at the same time permitting at any 
time the oversight of the status of the management, and hence also furnishing the 
needful basis for new organization work." In conformity with these purposes the 
Ledger is divided into a general and a special part. 

The general part, arranged according to subjects, contains in historical sequence those 
noteworthy changes, phenomena and occurrences which concern the whole Revier or 
large parts of it and are of a general nature; it takes up the noteworthy data recorded 
in the course of management as well as any suggestions regarding improvements. 

The special part of the Ledger is intended to record the events and changes occurring 
in the individual compartments; especially the changes in the stand produced by 
fellings and forestation; the logging costs are specified and explained. Certain sheets 
of a special map on a scale of i : 5,000, made for the use of the supervisor, form an 
addition to the Ledger and to the Area Register; on these are entered the changes in 
boundaries, the methods of using the soil and the stand changes made by fellings and 
forestation. If a road system has been planned, a road system map is put into the 
Ledger on the scale of i: 25,000, and also a blank map (on the same scale) on which the 
finished roads are entered. Detailed instructions for the correction of the maps are 
given in the manual. 

3. The Area Register. The status of the area of the reviers is controlled in its 
entirety by the Area Register, which consists of four parts: Section A, the map register, 
records all existing maps, surveys and working plan data; Section B records all area 
changes which have been begun; in Section C the entire area of the Revier is con- 
trolled and Section D records the transfer of soil intended for wood production to 
areas not intended for wood production and vice versa. 

B. Intermediate Revision (p. 233). The working plan is revised at the close of the 
first period (usually 20 years), but, in view of disturbances and changes in management 
occurring during the course of the period, an intermediate examination is undertaken 
in the eleventh year. To prepare for this the supervisor has to balance up the 
most important control books having reference to fellings arhd forestation. In a 
plenary conference, then taking place, a discussion ensues whether and in what respect 
there has been deviation from the regulations of the working plan or whether there is 
to be such deviation in the future. The working plan is then checked and revised as 
follows: (i) All changes in the felling time of standi of the first period; (2) the 
budget for the main yield according to the urgency of the necessarj- changes: (3) the 
felling budget of the intermediate yield; (4) the thinning plan for the next decade; 
and (5) if necessary, the road building plan. 

II. BAVARIA. 

The most important basis for forest organization has been up to this time the Instruc- 
tions of 1830 together with some supplementary directions. Essential prescriptions 
are also contained in the basic protocols and the revisional notes of the ministry on the 
individual working plans. New directions for working plans are soon to be expected. 
The most important points which characterize the past procedure are the following: 

(i) Preliminary Work and Bases (p. 234) (a) Subdivision. Large forests are 
segregated into districts, i.e. separate forest regions formed by natural conditions, units 
of contiguous location; they generally are named. 

The permanent units of management (formed by systematic division), and which are 
marked by Arabic numbers, are called compartments. They are formed in the plain 
by straight rides (Schneisen). In the mountains the division lines are adapted to the 
contours and connected up with the road system. Moreover the compartments depend 
on forest conditions and management. Their size and shape are often very dissimilar. 



Appendix i8i 

Changes in the existing division are avoided as much as possible. No positive direc- 
tions are given for the size of compartments. Varying parts of the compartments are 
separated as lots (marked with a, b, etc.). As regards their size no general prescrip- 
tions are given," but as a rule they are not to be less than 2j^ acres. Differences in 
stand within the lots (wind fall openings, regeneration groups, etc.) are recognized by 
numerical exponents (a', a' . . . .). Regarding the character and the direction of the 
fellings, general prescriptions are given in the management plan (which are elaborated 
for working units) and special prescriptions for periodic fellings. 

(fc) Basic Protocol (p. ^33). Before beginning the survey the main features of the 
plan of management are to be determined. This is done in a council of commissioners. 
This has reference to all conditions which are of essential influence on the wood pro- 
duction (soil, situation, increment, yield, market, legal conditions, etc.). Moreover 
the former management (in its most important technical and economic aspects) is dis- 
cussed. The future management plan in its main features is determined from the 
previous plan. At the same time there is given here the basis for the segregation of 
working groups occasioned by difference of species and of rotation. The results of 
this council meeting are recorded in a "basic protocol." 

(c) Description and Dcterviinaticn of Cut. The permanent bases for determining the 
cut (especially the site conditions) are stated for entire compartments, so far as no 
essential differences occur in their component parts. The conditions which are of a 
temporary nature, especially the stand conditions and measures of management, are 
stated for the lots. The description of the stand is to emphasize in the briefest possible 
manner the conditions which are of moment to the management, especially the domi- 
nant species, the mixtures, growth, density, and age. The age classes were hitherto 
so formed that each class comprised a period of a quarter of the rotation. In the 
future, the age classes will be established with 20-year periods (I. Class, 1-20 years, 
etc.). 

The determination of the growing stock is by complete calipering for the stands 
that are to be exploited during the next period, unless simpler methods are indicated 
by former surveys or by experience of past management. The growing stock of later 
periods, as far as it is to be determined at all, is to be estimated from yield tables on 
the basis of average increment. 

2. Working Plan, (a) Method of Regulating the Yield. The former method of 
yield regulation was a combined (area and volume) allotment (p. 236) method (Fach- 
werk) with 24-year periods. In recent times the yield regulation is confined to the next 
period, which in future will comprise only 20 years. The allotment of the areas is 
done by working groups, beginning with those under the longest rotation. Within the 
group the stands are enumerated according to the order of numbers of the districts, 
compartments, and lots. The working plan is to furnish a control over the manage- 
ment planned. The prescriptions are, however, so formulated that the management is 
not rigidly fixed for long periods. The allotment of the stands to the periods of the 
working plan is based largely on average age. Deviations from this rule are indicated 
by the condition of the stands and considerations of the establishment of a good felling 
series (which is helped by suitable severance fellings). 

(&) Determination of the Felling Bttdget. The yield of the stands (lots) is calculated 
by adding to the present volume the increment for half the period. The felling budget 
for the main cut is determined by multiplying the felling area corresponding to the 

rotation ( ' . if rotations vary for separated working groups) with the average wood 
r 

volume of the area unit of the stands to be felled. To this are added the volumes of 
deferred fellings and accidental yields. In case of irregular age class conditions suitable 
increases or decreases of the felling areas are made. The budget is stated in toto, 
not separated by species. 

The yields (special estimates by yield tables) of intermediate fellings are given only 
for the first half of the first period. The total volume of thinnings is also stated in 



1 82 American Forest Regulation 

per cent of the total yield and per acre of forest area. The annual budget of tlie 
intermediate yield is from estimated total volume divided by the number of years. 

(c) Special Manascvtcnt Plan. To give the management needful suppleness it is a 
rule to allot in the working plan more areas than correspond to the debit of utilization. 
Stands are allotted to the working plan (which in future is to be made for lo or 20 
years), which contain 15 to 30 times the yearly budget (p. 237). This affords the possi- 
bility of multiplying felling areas and making gradual progress with regeneration 
fellings. The "basic protocols" give directions to the supervisors for the location of 
fellings. 

Besides the felling plan there is a special forestation plan, which contains a list of 
forestation cost estimates arranged by lots. Plans are also prepared for the construc- 
tion and maintenance of roads (and eventually for the most important secondary uses). 

3. Control and Revision. The control of the fellings and stock estimates are carried 
on as in Prussia: 

(a) By annual comparison of the total cut with the budget. The tabulation gives" 
the main cut, intermediate cut, and total cut. 

(b) By periodic comparison of the felling results with the estimates for each lot, 
which is carried in a special record. At the end of the lo-year working period this 
Control Book is balanced. 

The periodic examination and revision of working plans, which may be either simple 
or comprehensive, is done by the Forest Revisions Bureau (Waldstandsrevisionen). 
The plans are "comprehensive," if important changes become necessary through extra- 
ordinary natural phenomena or for other reasons. Essentially, the revisions are carried 
on as in Prussia. 

III. KINGDOM OF SAXONY. 

The forest organization for a long time has been carried on by a separate bureau 
(Forsteinrichtungsanstalt), which has had special advantages for its development. 
Through this special bureau, the personnel is well trained and a uniform execution of 
(p. 238) all survey work is secured. The results of the working plans can be more 
effectively worked over and their relation lo other technical branches (experiments, 
administration, economics, statistics) more appropriately kept in view. In Saxony too 
the yield regulation is based on the allotment method (Fachwerkmethode). H. Cotta, 
who systematically carried on the survey and organization of the Saxon State Forests 
in the years 1811-1831. advocated the area allotment as well as the combined allotment. 
Due to the regularly recurring revisions, it was early recognized that the yield calcula- 
tions for later periods were superfluous. The allotment for these was therefore 
abandoned and the yield regulated only for the next decade. The most important 
points characteristic of the Saxon procedure have reference to (i) the preliminary 
work of estimating, (2) the determination of the felling budget and felling areas, (3) 
the control and revision. 

I. The Preliminary Work. The subdivision into permanent management units (com- 
partments) is (in the plains and in gently sloping country) done by a system of straight 
lines intersecting as far as possible at right angles. The main lines, so-called Wirth- 
schaftsstreifen (management lines or strips) run in most reviers of Saxony from north- 
east to southwest. They serve as boundaries of the felling series and are 9 yards wide, 
in order that along their limits breaks (i.e., severance fellings) may be formed as a 
protection against wind damage. The rides, which are located at right angles to the 
management strips are to indicate the direction of the annual felling areas and as a 
rule are 4.5 yards wide. 

In mountain reviers too, m the middle of the last centur}', the subdivision was carried 
out on similar principles, except that the division lines conform to the more important 
contour lines (ridges and saddles). With the progress in making roads (which came 
about independently of the subdivisions), many lines were replaced by roads. A sudden 
and systematic change of the existing subdivisions (as was carried on in the Prussian 
mountain districts) could not be carried out because of the prevalence of spruce, so 



Appendix 183 

liable to windfall, and because of the straight division lines along which severance 
fellings are made. In working out road systems (in each case), it is investigated 
whether and how far the roads are to be used as division lines and what changes (of 
the latter) are to be made in consequence of the new road system. 

The (p. 239) lots (stands) mainly due to differences of age, are segregated down to 
a minimum area of J^ acre. Binding rules are not given, however, in this regard. 
Local marking of the limits of lots is not attempted unless existing lines can serve. 
On account of the uniformity of stand conditions the descriptions of lots are made 
brief — in tabulated form. The soil classification is made by site and stand qualities. 
The former gives expression to the normal, the latter to the actual conditions of pro- 
duction. The segregation of sites is made according to the Instructions for Forest 
Experiment Stations. The stand quality is expressed in simple numbers, which show 
the combined effect of site and condition of stand. The age classes are stated in 20- 
year gradations (I. class 1-20 years, II. class 21-40 years, etc.). Each age class is again 
subdivided into decades. The resulting classification in decades is also shown on the 
stand maps. 

To ascertain the growing stock, the volumes of the stands below 40 years are calculated 
on the basis of yield tables (based on stand quality and age classes). The stock of stands 
over 40 years is ascertained by ocular estimate, which is done at each ten-year main 
revision. Calipering is the exception. With regular stand conditions, the predomi- 
nance of clear cutting, uniform stand management, the exact statistics of the results of 
former management plans, and the ability of the permanent personnel, the ocular 
estimate has hitherto given good results. 

2. The Determination of the Annual Felling Budget. Rotation, (a) Measure of 
Utilization. If a clear cutting system is employed, the normal annual felling area 
furnishes an easily applicable measure of the annual cut. The determination of the 
rotation depends chiefly on expert judgment (based on existing rotations, on the 
requiiements of the market, and on the price (p. 240) relations of the timber size 
classes). To determine the normal rotations investigations were formerly made for 
the spruce (which occurs throughout the whole country) and index per cents were 
calculated for characteristic stands. For the calculation of the volume increments per 
cents ample material is on hand. The calculation of the value increment per cent is 
based on the auction prices of the various timber size classes, which compose the 
average cubic meter of the stands of the various age classes. The value relations of 
the log sizes (which are classified according to a middle diameter of 6. 6-8, 8-1 1, 11-14, 
over 14 inches) indicate the value increment per cent. 

With regular stand conditions the normal felling area is observed as accurately as 
possible, which offers no difficulties in the prevailing clear cutting system. Under 
irregular conditions deviations become necessary. The age class condition serves as 
an indication of the degree to which these appear desirable or allowable. If the older 
age classes are in excess, more area is included in the felling budget, and vice versa. 
Great stress is therefore laid on an accurate estimate of the age classes. 

(b) Determination of Felling Areas. For felling during the next period of manage- 
ment, stands are chosen, which, according to age, soil, and stand conditions are mature 
in order of the need for felling. Next in importance in the choice of the felling areas 
is the regulation of the felling series. Since the spruce predominates, this consideration 
is of great importance for the whole country. Regard for the danger of windfall 
demands that the fellings proceed in a direction opposite to the dominant wind. 
Since the annual clear cuttings remain narrow and only gradually merge, tiie general 
rule is that the felling series remain short. 

In order to satisfy the demands of these felling rules and to counteract the dangers 
which the segregation (or grouping) of large, even-aged stands may provoke, it is 
necessary that one have command of a sufificient number of points of attack. To secure 
these, the boundaries of the stands must early be accustomed to an open position 
through the formation of low crowns, especially where those stands are located so as 
to be exposed to storm by the removal of old stands in front of them. This is accom- 



Ai)icrica>i forest Regulation " 



plished b}' making the iitannsc»tent strif>s sufficiently wide, by sci'crancc jcUin;j,s, and by 
cutting around those stands that can still develop a wind firm belt. 

(P. 241) The most important task of forest organization lies in properly locating 
the order of the felling areas. The contiguous felling areas assigned to the next 
management period should not be larger than the rules of the progress of fellings 
justify. The future formation of the felling series (their continuation, interruption, 
etc.) is dependent on conditions which (at the time of the making of the working plans) 
can not yet be foreseen. 

(<:) The Justification of the Fellifif^ BucP^et. The felling budget is listed separately as 
main cut, clearings, and intermediate cuttings (thinnings, cleanings and accidental cut- 
tings). After the felling area has been decided upon, the main felling budget is based 
on an ocular estimate of the growing stock (on the felling area). Estimating has 
proven sufficiently accurate for purposes of fixing the budget. To control the total 
estimated volume, the amounts per acre (of felling area) are compared with the results 
of the last decade's fellings; important deviations from the average hitherto obtained 
must be justified. The actual annual increment (which is calculated according to sites 
and age classes with the aid of the yield tables) also indicates the felling budget. To 
compare the increment thus obtained with the yield possibility of the revier, the normal 
increment is also calculated by site classes. 

The probable yields from thinnings are estimated on the basis of the results of the 
last decade (with the aid of yield tables) taking into special consideration the condition 
of the stands. The separation of broadleaves and conifers is made only if broadleaves 
form a substantial amount (of the stand). 

3, Statistics. The data collected by the working plans bureau (for every revier and 
for the whole country) date back to 1817, or in part to 1844. The importance of perma- 
nent records for working plans (p. 242) can best be shown by the Saxon yield statistics; 
therefore their results may find place here. The most important data are: 

I. The Age Classes. In the State Forest the present condition of the age classes is: 

Class I II III IV 



V 


VI 






open and bare :: 


Totals 


II 


2 :: 


100 



Per cent 23 21 25 18 

2. The Sites. According to the last accounts the qualities are: 

I II III IV V Average quality 



II 


III 


IV 


V 


36 


49 


II 


I 


16 


53 


25 


2 



Site qualities %: 3 36 49 u i :: 2.7 

Stand qualities %: i 16 53 25 2 :: 3-^3 

3, Growing Stock. This has in the second half of the iQth century increased from 
152 cubic meters to 187 c. m. per hectare of forest area (from 2173 to 2674 cu. ft.). In 
the last 30 years it has remained pretty much unchanged, 

4, Main Stand Increment. The normal increment corresponding to the site quality 
is estimated for i ha. at 6.18 cm.; the actual increment (corresponding to the stand 
qualities) at 4.84 cm. (88 and 69 cu. ft. per acre). The annual felling budget of the 
last revision period amounted on an average to 4.21 c. m. (60 cu. ft.). 

5. The Fellings on i Hectare of Forest Soil amount on the average to: 

1854-63 1864-73 1874-83 1884-93 1894-03 1894-08 
Timber 3.44 4.28 4-72 4-88 503 5-34 c. m. per hectare. 

Total volume 5.01 5-85 6.48 6.43 6.39 6.23 

6. The Proportion of the Timber Size Classes. The timber per cent has in the 
course of the past century risen from 17% (in the decade 181 7 to 1826) to 82% (1904- 
1908). 



Appendix 185 

7. The Income and Expenditure and the Net Yield in marks per ha. of the entire 
area amounts on tlie average to: 

1817-26 1827-36 1837-46 1847-53 1854-63 1864-73 1874-83 1884-93 1894-03 1904-08 

Income: 
17.5 18.6 20.2 25.6 35-4 491 62.4 66.7 76 90.4 M 

Expenditure: 
8.0 8.6 9.1 10.2 1 1.5 13.9 20.8 23.0 28.9 33-2 M 

Net yield: 
9-5 lo.o I I.I 154 23.9 35.2 41.6 43.7 47-1 57-2 M 

8. The Forest Capital was estimated (in marks per ha. of forest soil) to be: 

1854-63 1864-73 1874-83 1884-93 1894-03 1894-08 
1156 1417 1682 1859 2206 2311 M 

(P. 243) To calculate the forest capital, soil and stand values must be ascertained. 
The soil value is estimated for the average area of the different reviers on the basis of 
expectation values. The value of the growing stock (for stands up to 40 years) is 
calculated by cost value formulae. The interest rate is based on the relation of the 
net yield to the forest capital. 

4. Control and Revision. The felling budget (classed as final and preliminary cuts) 
is summed up as a total budget (the amount of timber to be cut and controlled is fixed). 
At the end of tlie lo-j^ear management period, a main revision takes place; and in the 
middle of the period an interim revision. In the main revision an entire redrafting of the 
working plan takes place (on the basis of a new valuation of the revier). In the interim 
revision, necessary additions and corrections are considered; especially; (a) forestation, 
(b) comparison of the felling results with the estimate, (c) deviations of the fellings 
from the plan and (d) miscellaneous. Moreover the nature of the revision is dependent 
on the changes in the forest management which have taken place (as compared with 
the working plan), while the details of the revisions are determined by the instructions 
on the formulation of new plans. 

5. Maps. For the management plan the Saxon stand maps are of the greatest 
importance; these show (on the scale of 1:20,000 or i: 15,000) the species, the age and 
the felling series. The felling areas of the next decade, the seqiience of fellings, the 
severance fellings and the liberation cuttings are specially marked on the maps. 

IV. wiJRTEMBERG. 

The Instructions (printed in 1878) for the elaboration and renewal of working plans 
had the combined allotment method as a basis. In the year 1898 these Instructions 
were changed and supplemented by new regulations which abrogated the area allot- 
ment plan and limited the regulation of the yield to the allotment (p. 244) of the felling area 
for the first period. These regulations are in force for State and institution forests. 
The most important regulations concern the preparatory work, the formulation of the 
working plans and their execution and revision. 

I. Preparatory Work. The regulations regarding the formation of working groups 
and the subdivision for management are of the next greatest importance (i.e., after the 
prescriptions for the determination of the felling areas, the surveying and mapping). 

I. The Forming of Working Groups. Different methods of management and diverg- 



1 86 



Anicrica)i Forest Regulation 



ence from the normal rotation are emphasized as reasons for their segregation. For 
each working group an independent age class relation (with special order of fellings) 
is to be attempted and a special felling series established. 

2. Subdivision, (a) Districts. As a rule the different large forest areas of an 
administrative unit are segregated as districts. Their main purpose is to afford a 
simpler orientation. 

(b) CoDipartmcnts are considered as the pcr»iancnt local cornerstone of management. 
It is intended in the course of time to eradicate the differences occurring within the com- 
partments (and lots) which on account of their form and size do not seem convenient. 
The average size of the compartments in moderately large working groups, for broad 
leafed trees and conifers, must not exceed 35 to 50 acres. Their boundaries should be 
located as far as possible on natural contour lines and on roads to facilitate easier 
identification, to economize area, to protect the edges of stands and to enable the 
careful skidding of logs. "The main road system generally forms the basis of the 
subdivision." 

(c) Lots are the unit for the felling and silvical measures of the working plans. The 
reasons for the segregation of lots (not to be too rigidly carried out) are: 

(P. 245) I. When the stand and soil on a part of the compartment is so different 
from the rest that a similar management (especially simultaneous regeneration) cannot 
take place; 

2. When some species occurs other than that dominating the compartment; 

3. When the dominant species shows a variation in age of over 20 years. 

The boundaries of the lots are generally not marked in the forest. The lots are 
shown on the map by small Latin letters, which also indicate the age classes (a = 1-20, 
b =^ 21-40, c =: 41-60 years, etc.). 

(d) Fcllifig Area Division. In coppice and coppice under standards only the division 
into yearly or periodic fellings is necessary. 

II. The Working Plan. The general order reads: "The entire management is to be 
so regulated by tlie working plan that its purpose may be attained as quickly and as 
completely as possible — the most advantageous use of the forest, — at the same time 
securing a sustained yield, and with due consideration of the objects and needs of the 
owner." 

I. Form of Presentation. The most usual form of the working plan (from several 
in existence) is: 



Sub-Compartment 



5 < 



ha. 



Stand Description. Age-Classes 



Years 






Species 

and 

Stand 

Form, 

Relation 

of 
Mixture. 



1 I 



e d ! c b 



Hectare 



•o S 



Cultures I 



Area-plan fli 



III 



Main Yields of I Period. 



Area -Basis' 



Hectare 



Yield (timber wood) 



I. Decade 


?5^ 


Cu. 


„j_ 












=«i. 




0^ 


m. 



Decade 






Cu. 



2. Economic Data. The stand descriptions are brief and are limited to the essential 
points necessary for clearness. The recent yield tables of Lorey, Weise, Wimmenauer, 
and Eberhard form the basis for site classification (which relates to the dominant 
species — if in the first decade a change takes place by planting other species). It is 
given by lots, if differences within the compartments are to be emphasized, otherwise 
by compartments. The average age of the dominant stand (determined for the manage- 
ment) is used. Stands with sharply defined age classes (especially those in process of 
regeneration) are assigned to different age classes according to the proportional area 
occupied. 

3. The Area Regulation Plan (p. 247). In contrast to the former rules for the allot- 



Appendix 187 

ment method, at present only the area for the first 20-year period is actually allotted. 
The standard for the utilization area to be segregated, is the normal area of the 20-year 
period; but where there is a deficiency of mature stands, this is reduced, and if an 
excess above the normal amount, it is increased. The recording of the areas is by lots. 
If a lot is only partly assigned to regeneration in the first (I) period, only a correspond- 
ing part of its area is to be allotted to the (I) period (except for special cases); the 
remainder is left out of consideration (i.e. in group regeneration cuttings, seed fellings, 
etc.). In choosing the stands to be regenerated, the following must be weighed: a 
consideration of these stands themselves, a good felling series, and an arrangement of 
stands with a corresponding local distribution of age classes. A development of the 
stands (injurious to the technically correct cutting) must be prevented by sufficiently 
earlj- liberation and improvement fellings. In large conifer areas, a gradual formation 
of short and, so far as possible, independent felling series must be particularly striven 
for. Accurate stand maps (colored if possible) are to be used for planning the work 
(on which measures are also to be noted). 

If, for the purpose of enlarging the basis of the area plan, it appears desirable to 
consider the second (II) period as well as the first (I), its area must be also 
segregated. 

4. Plan for the Main Cut. Up to the year 1898 the regulation of the main cut was 
in accordance with the simplified combined allotment method (described in the literature 
of Grebe, Graner, and Stoetzer). At present the regulation of the yield is limited to 
the first (I) period. The total of the lot yields assigned to the (I) period forms the 
basis for the periodic budget. These yields are determined according to the condition 
of the stand, and after a consideration of the felling series and the age class relations. 
Accidental fellings are to be added to the cut (from the stands not included in the 
felling plan of the (I) period); .... these are estimated according to average 
conditions without trying to consider (p. 248) the amount produced by unusual natural 
phenomena. The main felling budget of the next decade is, as a rule, to be put at half 
the yield of the first period. All yield data refer to timber. The volumes for the (I) 
period are usually secured by calipering 100% of the stand. 

5. Area Plan of Thinnings. For carrying out the secondary fellings of the first 
decade either a mere area plan is provided, or else in addition an estimate of the timber 
yield (in cubic meters). All secondary fellings are to be treated as thinnings without 
reference to the age of the stand. 

6. Other Matters in Working Plans. Besides the plans named there must be added 
to the working plan: an area plan for cleanings; an area plan for the forestation to 
be carried out in the first decade; and a plan for the use of litter. 

7. Statistics. Since the year 1882 annual reports are made, which give the results 
of the management of the past year. These also include periodically the results of 
the working plans. 

III. Execution and Revision of Working Plans. I. Control. "In carrying out the 
main fellings in the timber forest," says the forest service manual, "as well as in 
standards (coppice under standards forest) a volume control is applied so far as a 
budget of volume has been set. For the secondary fellings (in the timber forest and 
in the coppice under standards) an area control is to be used so far as the working 
plan provided for thinnings." The unit controlled includes the cubic of timberwood 
(Derbholz, 3 inch diameter and over). 

II. Renewal of Working Plans, (a) Main Revision, (p. 249). This takes place 
at the termination of a decade. Either an exhaustive revision of the working plan in 
its essential parts is made, or merely a correction of the existing plan (especially as 
regards the fellings and forestation) depending on the changes which have or are to 
take place during the decade, through natural occurrences or economic conditions. 

(/') Interim Revisions. In timber forests of more than 750 acres an interim revision 
is made at the end of five years; this considers mainly the felling budget and the 
influence of any natural injuries on the utilization. 



x88 Aiiicricaii forest Regulation 

V. BADEN. 

In Baden also the yield regulation has been first of all by the allotment method 
(volume allotment). This method, however, did not ai>i)car suitable under the preva- 
lent forest conditions which are characterized by natural rej,^eneration (especially silver 
fir). Since the regeneration of the fir (including the preparatory cuttings) required 
much longer than the 20-year periods, the management could not be adapted (as is the 
basic condition of a good method) to the framework of the yield regulation. 

For about 60 years decennial revisions have been made in Baden working plans. 
The results (the budgets actually realized and their effect on the condition of the 
forest) form an important basis for practical management. The present method was 
introduced in the year i86g. Essential changes in the present rules are expected in 
the near future as evidenced by the literature. The most important points of the 
Baden method are: 

1. Preparatory Work (p. 250). Before drawing up a working plan there is an inspec- 
tion of the forest by the officials charged with the work and the last plan is care- 
fully investigated in all its details. This investigation includes the subdivisions of the 
forest, the former site and stand descriptions, the estimate of the growing stock and 
increment, the results of the previous working plan and the principles underlying the 
future management. 

The general descriptions refer to the data on the site conditions, the existing species, 
method of management, rotation, management rules, etc. For each compartment or lot 
there is a brief description of the area, the stand, the growing stock and the increment. 
The growing stock in the compartments under regeneration is calipered; elsewhere as 
a rule it is estimated by yield tables, past experience and by sample plots. For a long 
time special weight has been laid on the estimate of the current increment for regulation 
purposes because of the present stand conditions (there was otherwise no sufficient 
basis). The importance of increment for the regulation of yield is emphasized in the 
most recent instructions. In the report, yield tables and sample plot data are used; 
but in the elaboration of the working plan special local investigations are also made 
(in suitable stands). Besides the current increment (which is the objective of such 
investigations) the mean increment at the felling age (accepted rotation) is also 
established. 

2. Determination of the Felling Budget. The determination of the felling budget is 
derived by Karl Heyer's method (i.e. felling budget =: total increment in period of 
regulation plus difference of actual and normal stock divided bj^ period of regulation). 
The actual increment is thus the main basis and measure of the felling budget. This 
increment was conceived and determined according to the Instructions of 1869 as 
current increment, "as it will probably take place in the next decade." In consideration 
of the difficulty of an accurate calculation and the limitation of the use of the results 
of the calculation on the main felling budget, it appeared advisable to let the mean 
increment at fellirig age take the place of the current increment (p. 251). 

The growing stock is estimated for all age classes according to the actual volume of 
the stand. In each age class the normal stock corresponding to it (to be ascertained 
by the use of yield tables) is employed for comparison with the actual growing stock. 
The total normal growing stock is besides to be determined according to the formula, 
increment on total area for half the rotation. "More than the increment is to be used 
if an excess above the normal stock exists, the utilization of which appears silvically 
and economically advisable. Less than the increment is to be used when the full 
normal stock is not yet in existence. In the latter case the quicker the normal stock 
can be attained (by saving of increment) the better, provided that in doing so no 
essential economic loss or mistake in management is caused; in no case, however, shall 
the equalization period be longer than the rotation. With these principles in mind, 
the felling budget is determined for each given case according to forest conditions and 
the special needs of the ow-ner; Init it must not be forgotten how undesirable it would 



Appendix 189 

be, for communities and corporations, to have any considerable variation in the felling 
budget in the various decades, and how greatly this variation would detract from the 
standing of forestry. A steady gradual rise in the felling budget will be considered 
much more desirable by every forest owner, rather than a rapid rise, which must be 
followed by a considerable fall later on; the reverse is also true. Moreover, it is to 
be expected that in almost every decade, extraordinary happenings and needs make 
extraordinary utilization necessary, and that therefore very often the established budget 
must be exceeded. In case of doubt therefore, it is good policy to be conservative. To 
the main budget (figured as above) the secondary fellings are to be added according 
to estimate. Overcuts and undercuts, which (according to the rules of management 
are to be compensated for in the new decade) must, in so far as they afifect the main 
cut, be considered when the new budget is decided upon. The budget for the coppice 
and coppice under standards forests, which are regulated by area, is the actual yield 
of the annual felling area (and is thus determined by area and not by volume). 

3. Statistics (p. 252) are closely connected with forest organization. A uniform 
method of statement was established in Baden in 1869 to simplify the general descrip- 
tions in working plans, and to obtain good data on forest history and yields. The 
administration officials begin the statistics, which are continued and completed by the 
estimators when the working plans are revised. The importance of good connected 
statistics for forest organization is clearly recognized in Baden. The most important 
statistical data are: 

1. The Rotation. In the State forests 59.-4% of the area is under 120 years rotations, 
26% 100 years, 0-4% 90 years, and 3.4% 80 years. 

2. The Increment. The actual volume increment at felling (rotation) age is placed 
at .{.0 cubic meters; the normal is 5.4 in the State forests. 

3. The Growing Stock. This is shown since 1862, when it amounted to 220 cu. m. 
for the timber forests, a steady increase up to the present figure of 290 cu. m.; the 
normal growing stock is estimated at 299 cu. m. 

4. The Felling Budget. This amounts (according to present conditions) in main 
fellings to 4.5 cu. m., in secondary fellings to 1.6 cu. m. The cut has increased from 
4.67 cu. m. in the year 1867 to 6.31 cu. m. in the year 1907. 

5. Average Prices (for log classes according to the Heilbronner standard). The 
average price per cu. m. has risen from 8.63 marks in the year 1867 to 13.71 M in the 
year 1907. 

6. Income, Expenditures and Net Yield. The income per hectare has risen (1867 
to 1907) from 44.03 M to 89.86 M; the expenditures from 36.9 M to 41.8 M, the net 
yield from 26.77 M to 52.31 M (with normal exchange, about $3.70 to $4.20 per acre). 



VI. GRAND DUCHY OF HESSE. 

The directions and aims which are followed in formulating working plans are charac- 
terized by the words: "The management (p. 253) of the State and communal forests is 
to be directed, with adequate consideration of the needs of the present, so as to increase 
the yield (qualitatively and quantitatively) as quickly as possible to the highest possible 
amount. In order to attain this object, the aim must be to bring the actual increment 
as nearly as possible to the normal." 

The most important measures for the attainment of the normal yield condition are: 

early utilization of poor stands, choice of species adapted to the site, technically 
correct forestation, thorough care of the stand, and rational thinning practice. The 
most important prescriptions in the Instructions refer to: 

I. The Construction of the Stand Table. The document most characteristic of the 
working plan bears the title "Stand Table and Management Book (Wirthschaftbuch)" 
and is drawn up according to the following scheme: 



190 



American forest Regulation 



District and Compaftment. 



Wooded Area — ha. 



G 


roup 




• 

Site and Stand 
Desc, Soil, Situa- 
tion, Exposure, 
Species in 
Decimals of Stand. 
Justification of 
Management 
Hitherto. 


Aim of 
Management, 


'0 

« 

c/5 be 


Si 

fl) • — 


Growing Stock in 
Timber-and Brush- 
wood According 
to Yield Table. 




and Measures H "^ 
for next "^ c 
Decade. - 


For 

I 
ha. 




lit 


Area. 


For the Group 
or Compart- 
ment. 




ha. 


jhis 








Cu 


cu. m. 


I. 


2. 


3- 


4- 


5- 


6. 


7. 


8. 








1 















Actual Grow- 
ing Slock 
in Timber- 
and Brush- 
wood for 
Group 
or Compart- 
ment. 


Growing Stock 
in Over-wood Volume. 


Curre 

Normal 
Increment 


nt. 

Actual 
Incr. 


Estimate of Yield in Timber-and 
Brushwood Expected in next Decade. 



U 


Main Yield. 

X ^ b) Other 
a) Over- /- . 
' , Mature 
wood T,. , 
17 , Timber 
Volume ^ , 
Cut. 




re 

c 
_o 

u 

3 


For next 

10 Ycai^ in 

Timber-and 

Brushwood on 

the Average 

Per Year and ha. 


Intermediary 
Fellings. 




In the Group 
or Compartment. 


Per 
ha. 


In the Group 
or Compartment. 




cu. m. 


cu. m. 


cu. m. 


9- 


10. 


II. 


12. 


13- 


14- 


15. 


16. 


17- 





















The following explanations are also given (p. 255): Parts, within the permanent com- 
partments (Abteilungen) are segregated as lots or groups (Gruppe), which differ from 
each other so essentially in site, species, age, growth, etc. that they must be under 
special treatment. The groups are designated on the maps by small Latin letters and 

are locally bounded by shallow ditches The organizer decides whether 

the parts (as small as .7 acre) of the compartment are adapted by situation, size and 

shape to special management If groups are based on site, they assume 

a permanent character; but if based on the condition of the stand they are teinporary. 
These differences are in the course of time, to be diminished or eradicated. The site 
and stand descriptions follow the rules of the Forest Experiment Stations. Measures 
for the essential establishment and development of the stands are given in the stand 
descriptions. 



Appendix 191 

The objects of management (as the stand appears at the time of survey) are entered 
in the plans; as a rule the local officer in charge cooperates directly in drawing up the 
working plan. The "objects of management" are not, however, binding for all time; it 
is only to assist newly appointed officials and changes may. be ordered at the time the 
annual working plan is drawn up, or be agreed upon at inspections. The urgently neces- 
sary measures of the next 10 years are to be briefly stated by the administrative officer. 

In mixed stands the main species determines the management. Height forms the 
most important basis and measure of site classification. In every lot or group the 
average height of the stand is determined by measuring several stems of about medium 
height; on the basis of this height and age, the site classes are established according 
to the standard of current yield tables. The normal growing stock is also taken from 
the yield tables; the actual growing stock is found by multiplying the normal stock 
by a reduction factor, which like the full yield factor in Prussia is expressed by a deci- 
mal (p. 256). The current (normal and actual) increment, which appears in the stand 
table, refers to that part of the total increment, which goes into the permanent stand. 
The normal increment is found by subtracting the growing stock volume of the main 
stand (as found in the yield tables) at age (a) from that at (a — 10) and then dividing 
the difference by 10. The actual increment is found by multiplying the normal incre- 
ment by the full yield factor. 

2. The Calculation of Growing Stock and Increment. In order to give the total 
normal increment and normal growing stock, a statement of the site classification for 
the future main species is required. The normal increment, arranged according to 
species and site, is calculated as mean increment at felling age. On the basis of the 
conclusions of such a statement the normal increment and the normal growing stock 
may be figured from current yield tables. The calculation of the normal growing stock 
is made under the assumption of regularly graded age classes (I. 1-20, II. 21-40, etc.) 
the normal area of which is determined by their relation to the total rotation. The 
estimates of yield are made to the middle of the age classes. By adding the estimates 
of the different site classes, normal increment and normal growing stock for the dif- 
ferent species is obtained. The total normal increment and normal growing stock is 
then found by adding the figures for the different site classes. The age class table 
serves as a basis for the statement of the actual growing stock; the area and the actual 
growing stock in timberwood and brushwood is given for every age class. At the end 
of this tabulation, the areas and growing stock of each age class are compared with the 
normal age classes and, the normal growing stock. The budget is based on the 
result 

3. The Protocol of the Council. After the preparation of the data cited above, a 
protocol of the council is taken down which is to be submitted to the ministerial divi- 
sion for approval. This must cover: the species to be planted or to be favored in the 
future, the rotation, the possibility of a uniform period of organization, the sequence of 
thinnings, the present silvicultural method of management, any contemplated changes, 
tlie normal felling area and the formulation of management rules. 

4. The Formulation of the Budget and the Method of Utilization. (Logging Prac- 
tice). I. Felling Budget (p. 257). A. Utilization in Mature Timber. The normal 
felling area forms the basis for utilization, covered by the working plan. If the stand 
conditions are^ regular, it is sufficient to draw up the felling plan for a decade. Irreg- 
ular conditions may indicate the desirability of planning the expected fellings for two 
or more decades. Deviations from the normal fellings are to be mainly justified as 
follows: 

(a) The Relation Between the Actual and N'orDial Grozi'ing Stock. Present differences 
are to be diminished unless a change of rotation is contemplated. To determine the 
propriety of felling a growing stock surplus or of making up an existing deficit all 
silvicultural and financial conditions must be exhaustively considered. 

(b) The Age Class Relation: The growing stock of the 2 or 3 oldest classes is to be 
especially considered; if the actual growing stock does not differ essentially from the 



192 ADicricaii Forest Regulation 

normal and if an appropriate part of the stock is found in the 3 oldest classes, the 
sustained yield may be considered as assured. 

(c) The Relation of Fellings to Increment. A comparison of the felling budget with 
the actual increment gives an indication whether, in the next decade, a diminution or 
increase of the growing stock maj' be expected. 

2. Determination of the Felling Areas and Progress of Regeneration, Areas of slow 
growth, where the increment differs most widely from the normal, should be felled 
first. Stands are chosen for the felling budget upon the following basis: I. Stands in 
need of felling: (a) Stands and parts of stands with poor increment, (b) remnants of 
high forest, improvement fellings, and clearing for roads, (c) parts of stands which 
must be sacrificed to establish a felling series; TI. Mature Stands (p. 258); III. 
Questionable Stands. Great stress is laid on a regular felling series and a good dis- 
tribution of fellings. Large areas of even-aged stands are to be limited as much as 
possible because of the dangers from storms, insects, etc. and to facilitate the local 
distribution of wood supplies. The Instructions prescribed, therefore, the formation 
of short felling series with cross-roads, railroads, rides, roads, watercourses, valleys, 
mountain crests, etc. as boundaries. 

3. Determination of the Wood Volume. The following rule is of interest: "The 
stands selected for the main felling budget for the next 10 years generally need not 
be calipered; the volumes of the felling budget can be based on yield tables or on 
estimates. Errors in estimating (due to this mere approximation of the main felling 
budget) if they are established at the time of felling, may be corrected by changing 
the felling budget within the lo-year management period or at the close of the period. 

II. Secondary Fellings. The thinnings (whose yields are entered in the table above 
mentioned) are listed in an area and volume budget corresponding to the main yield. 
The area budget is so made that about i/io of the total area to be thinned is felled 
annually, so that the felling is extended equally over younger and older stands, and if 
need be over stands of different species. The yield estimate is based on the yield 
tables, after carefully considering the actual conditions of the stand in question. Con- 
sidering the difficulty of establishing and executing adequate thinning budgets, a rule 
has been made, that, at the close of the annual working plan, a compilation of the 
periodically thinned areas must be prepared. If it is found that according to this area 
statement, the secondary fellings are not progressing fast enough, the secondary felling 
budget must be increased accordingly. 

5. Mapwork (p. 259). The stand maps made to accompany the working plan on 
the scale of i : 10,000 show the age classes by color, the species by tree figures, the sites 
b}' broken lines. 

6. Control. An efficient control covers the total felling, main and intermediary, 
timberwood and non-timberwood. 

Vll. GRAND DUCHY OF SAXONY. 

The Preparation of Working Plans (including surveys and check of management rules) 
is assigned to a special bureau ("Taxation Commission") whose president directs all 
work. Assurance of a present and future sustained yield is considered of first impor- 
tance in forest organization, provided forest production maintains and increases the 
fertility of the soil, and the highest yields are produced in the shortest ^possible time. 

The subdivision into permanent management units (compartments) has been carried 
out in a systematic way; in the plains by a net work of regular lines and in the moun- 
tains via contours connected with the road system. The average size of compartments 
is about 62 acres, and lots, if adequate stand differences exist (which form the basis 
of the management), are segregated to a minimum size. 

Stand volumes for the first decade are secured by special stock taking, which gives 
for each stand: number of stems, diameter, height, form factor, increment in diameter, 
basal area, volume and increment per cents. The results of the volume calculations 
are filed with the Commission. The forest experiments on yield are connected up with 
forest regulation; in fact the president of the "Taxation Commission" directs the estab- 



Appendix 



193 



lishment of sample plots where the influence of the various methods of stand 
regeneration and treatment are studied 

In each lot, description, area, site, age, height, and character of the stands are to be 
noted and (p. 260) entered in a survey register, which contains also the preliminary- 
rules for management. At the same time the age class table is drawn up and placed 
opposite the periodic felling area plan. 

The method of yield regulation is the combined allotment, which was upheld in 
literature by Grebe, for many years the director of the Grand Ducal forest organization. 
At present it is only used in its simplest form, in such a way that the yields are only 
shown for the first two periods. The main working plan is therefore to be formulated 
according to the following form: 



Results of Management. 



There Was Felled: 



Forestation: 



> C 



Area. 



Volume. 



18. 



ha. 



19. 



cu.m. run 



Designation | Plant 
of Felling i and Seed 
Method , Supply. 
and Number I Character 
of I of 

Record. Forestation. 



22. 



Area. 



ha. 



23- 



Costs. 



Secondary 
Uses. 



pf. 



24. 



25. 



The areas and volumes of the first (20-year) period are shown separately for the 
first and second decades. The timber yields in cubic meters are derived by adding the 
increment (up to the middle of the utilization period) to the present volume. The 
annual main felling budget is found by dividing the budget of the first decade by 10. 
Thinnings are regulated by area, but volumes are checked by local yield table estimates 
and special investigations. The control of fellings and forestation is according to the 
following scheme: 



Property. 



Designation 

and <; 

Character. 



CJ 



ha. 



Actual Growing Stock. 



Volume 

and 

Increment. 



per 
ha. 



Regulated Management. 



I 20 Year Period, 
from to 



I. Decade, 
from to 



Wood Yield, 



be . 

c rt 

~ 4) 



per 
ha. 



Total. 



ha. 



2. Decade 
from to 



bo 



ha. 



Wood Yield. 



per 
ha. 



Total. 






194 



American Forest Regulation 



II 20 Year Period, 
from to 


ri -a 
4J 


IV 20 Year 
Period. 


V 

a, 
> 


> 


Reforestation 

Area 

i:> First Decade. 




be 


Wood Yield. 


Rules of 




per ha. 


Total. 


Management. 


ha. 


cu. m. 


ha. 


ha. 


ha. 


ha. 


ha. 























The volumes of actual thinnings are compared with the budget. Revisions occur as 
a rule every 10 years (p. 261). The policy concerning silvicultural methods, rotations, 
as well as all conditions influencing the treatment of the forest must be clearly stated. 
The revised tables must show first of all the results of management during the past 
decade; next the plans for the coming decade. Otherwise the (working plan) revisions 
(which are similar in detail to those adopted by other states) depend on the changes 
which have taken place in the condition of the forest during the last decade. 



Areas. 



.2 «■ 

■o be 



ha. 



Wood Yield. 



Fuel wood. 



.c-o 
" o 






>^ 




Ui 




rt 








T3 


br 


<u 


c 


fi 










1> 




i, 


C 




'"' 





Cultures. 



ha. 



O 



M. 



Special Data 

as to 

Method of Felling 

and Cultures. 



VIII. ALSACE-LORRAINE.* 
When formulating new working plans (for forests for which there are no plans, or 
if there are plans, after the expiration (p. 262) of the 20-year period, after essential 
changes in area, after considerable overcuts due to windfall, insect injuries, etc., or 
when changes to other silvicultural methods are contemplated) a preliminary project 
(which must include the map for subdivisions and road-system as well as regulations 
regarding the methods of management and rotations) is drawn up by the revier super- 
visor; this is examined by the Forest Inspector and finally accepted by the Minister. 
The most important regulations for the formulation of working-plans are: 
I. Subdivision. The formation of permanent management units (compartments) is 



* See also the discussion in "Studies in French Forestry" already cited. German 
Forest Management in Alsace-Lorraine, now restored to France, is of special value to 
the student of regulation, especially when compared with French technique. 



Appendix 195 

connected up with the road sj'stem. Tlje area of the compartments must not as a rule 
exceed 25 to 37 acres in conifer stands, or 37-50 acres in broadleafed stands. Coppice 
and coppice under standards are subdivided into yearly felling areas as the local basis 
of management. In communal forests (as was prescribed in the ordinances of Colbert) 
one fourth the area is first to be set aside as a reserve. No binding rules are given for 
the formation of lots. In large forests (if several species are concerned) the smallest 

lot is 2.5 acres, provided a good boundary is possible, otherwise 5 acres 

where stands are being regenerated .... 2^ acres .... or if old 

timber is clear cut The lot corners must be marked locally by stakes and non- 
continuous ditches and entered on the maps. The compartments are labeled as in 
Prussia with Arabic numbers, fellings in coppice under standards and selection forests 
with Roman numbers, lots with small Latin Letters, while non-forest soil is indicated 
with German letters. With new subdivisions (p. 263) the numbering of the compart- 
ments and lettering of the lots is from the northeast towards the southwest, so that 
compartments and lots always bear higher numbers or later letters towards the wind 
direction. 

2. Surveying and Mapping. Survey work is as a rule limited to changes in interior 
sulidivisions, since usable maps exist for the whole country. After the survey of 
the compartment and lot lines, highways, roads, and water courses, etc., the special 
map (or office map) is to be brought up to date by the working plans officer. With the 
corrected special map as a base, a control (Uebersicht) map, which differentiates the 
species by color, is to be made on the scale of 1:25,000. The dates of utilization are 
only given for the areas assigned to the (I) and (II) period. The symbols used are: 
(I) first period areas, (II) second period, (I. II.) areas to be regenerated within 40 
years, (Pi.) selection stands, (S.) scenic forests; areas designated for oak reproduction 
(at least H acre in area) are outlined in red on the management map and must be 
marked in the forest. 

3. The General Description of the Revier digests the characteristic features of 
management regarding the general condition of the revier (as regards ownership), 
boundaries, survey, etc., site conditions (climate, configuration, soil); the occurrence 
and preservation of the main species; the previous management and its results; future 
management, especially the species, methods of silviculture, rotation; formulation of 
management regulations for fellings, for regeneration and development of the stands, 
the location of the road system and subdivisions; the wood market, secondary uses, 
hunting, etc. 

4. Special Description of Site and Stand. Site classes are given as a rule (if the 
lots do not show decided differences), for the whole compartment. They are based 
on the yield capacity (as compared with existing yield tables). Descriptions of situa- 
tion, soil, and stands are as agreed upon by the Union (p. 264) of Forest Experiment 
Stations. The mineral content of the soil, its freshness, depth and humus content is 
gauged by sample borings; stand descriptions are brief to the exclusion of all unessen- 
tial or self-evident statements. 

5. Segregation of Age Classes. Age classes are formed for each species; when 
different ages occur the areas are separated, especially stands under regeneration where 
the wood volume is divided into old timl)cr and young growth. 

6. Measure of Utilization and Periodic Area Division. The normal periodic area 
serves as a measure for the periodic cut in the present management period. If all the 
stands are to be managed under the same rotation, the normal felling area for a period is 
obtained by multiplying the area by 20 r. (where r = rotation). If several rotations are 
used, the normal periodic felling area is similarly determined for each species sepa- 
rately; the total felling area is then found by adding up the areas for each species. 
The stand volumes for the first period (in which regeneration cuttings have begun) are 
reduced in accordance with the age classes. A further allotment of stands for the III, 
IV, V, and VI periods is not made; these are simply listed in the column "Later 
Periods." In selecting the stands for the periods, their age and vigor must be taken 



196 American Forest Regulation 

into consideration. In conifer stands the formation of short felling series is recom- 
mended. Tlie rigid allotment method is no longer in use in Alsace-Lorraine. 

7. Scaling and Listing of Wood Volumes. Because of large contiguous stands of 

old timber and the long regeneration period (p. 265) the periodic area 

usually includes two periods. The volumes of all uncut regeneration fellings (Nach- 
hiebsreste) of the (1) period as well as the mature and nearly mature stands of the 
(II) period are usually calipered. In regular stands of the (II) period the growing 

stock is approximated by sample plots The volume of the second period 

is subtracted from the totals of the two periods .... increment (calculated to the 
middle of period) added to determine felling budget 

8. Felling Budget. This is obtained l>y dividing the totals of the volume measure- 
ments by 20. The felling budget, calculated in cubic meters of timberwood, is listed 
separately for the main and secondary fellings, by the four species groups: oak, beech, 
other broadleaved trees, conifers. In the communal forests a quarter of the area is 
held in reserve from the calculated main felling. 

9. Regulation of the Yield in Coppice and Coppice Under Standards. The yearly 
cut in these forests is arranged in regular sequence in flooded districts in the direction 
of the water flow. In coppice under standards the standards are calipered (and 
calculated) by age classes 

ID. Regulation of Yield in Selection Forests. The felling budget is calculated from 
the actual increment and according to the relation of the actual to the normal growing 
stock (by the K. Heyer formula, felling budget = actual increment -f or — difference 
of actual and normal stock divided by "equalization" period). To get the actual grow- 
ing stock all stems 3 inches and over are calipered. The actual increment is (p. 266) 
determined (p. 266) by special investigation on stems of different diameter classes: 
the normal growing stock is figured by the formula rotation X mean increment (at 
felling age) divided by 2 (or mean increment at felling age multiplied by half the 
rotation). The length of the "equalization" period is determined in each case. The 
cutting cycle is usually short, i.e. 7-9 years. 

11. Forestation and Road Building Plans are always included in the working plan. 
The Forestation plan includes; formation of stands, nursery work, seed collection, care 
of felling areas and trees, .... emphasis is laid on the care of the soil .... irriga- 
tion and drainage .... protection ditches and leaf catches. For the planning, build- 
ing and maintenance of logging roads detailed and careful directions are given. 

12. Working Plan Revisions take place in the middle of the 20-year period. The 
kind and extent of the work to be undertaken is dependent on the demands which are 
made on the working plans, and the changes which have occurred through management 
or through outside influences, in the first half of the management period. The data 
include; changes in area, annual felling volume and its comparison with the working 
plan, compilation of the final cuttings and comparison with the estimated yield, extra- 
ordinary fellings, secondary yields, execution and cost of forestation, changes in servi- 
tudes, influence of secondary logging, the road building, etc. 

IX. AUSTRIA. 

The most important technical instructions for the organization of the Austrian State 
forests concern : 

I. Subdivision of the Reviers (p. 267) begins, where necessary, with the segregation 
of the protection and "ban" forests. Special protection belts are set aside where the 
forest reaches timber line .... The commercial forests have: management classes, 
felling series, compartments, and lots. 

(a) Management Classes. Different working groups .... are formed for large 
contiguous forests because of differences in: transportation or market, method of 
treatment (high forest, coppice, etc.), method of cutting (clear cutting, natural regener- 
ation, selection forest, etc.), rotation, or existing limitations of management. 

(b) Felling Series. The working groups are divided (where sequence of fellings is 



Appendix 



197 



of consequence), into felling series, which are defined as "a contiguous series of felling 
areas." Their formation is dependent on the contours, the species and the kind of 
regeneration. The size of the felling series is determined by the size of the manage- 
ment unit, species, method of management, logging and transport conditions, but should 
not as a rule comprise more than three compartments. The boundaries of the felling 
series are formed along contours, or by roads, fire lines, or management strips opened 
up along the division lines to a breadth of 15-25 feet to develop windfirm border trees 

.... Younger stands exposed to the wind are protected by severance 

fellings 

(r) Compartments. The boundaries of the management classes and felling series 
form the framework of the compartments .... adapted .... partly to the moun- 
tain ridges and valley depressions, and to the existing roads, railroads, etc. Where 
these (p. 268) do not suffice for subdivision boundaries, artificial rides are made .... 
The length of compartments (which corresponds with the breadth of the felling series) 
is 2400 to 3000 feet — the breadth about 1800 feet .... 

(d) Lots. The reasons for forming lots are differences in: management and treat- 
ment, species in pure stands, mixture . . . .; mean stand age (10 years in young pole 
high forests, 20 years in old timber), in site class or yield capacity when these clearly 
show themselves in the uneven development of the same species, especially height 
growth, on contiguous parts of an area, in stocking, need of reforestation .... 

In the forest, the lot boundary lines are shown by small signs, shallow blazes, painted 
rings, timber scribe marks on trees and poles in old stands, and by narrow lanes in 
young growth. 

2. Survey and Description of Forest Conditions, (a) Preparation of Yield Tables. 
It is generally prescribed in the organization of State forest reviers that yield tables 
shall be made for the dififerent methods of treatment, species and site classes. These 

are based on carefully selected and combined sample plots (p. 269) The data 

secured are as follows: 






Main Stand. 



i/i 




^ rt 


S M 






S^ 


S u s 




,2 « 


.:2<cH 


£/5 U) 


Q^ 


OQ 





At Breast 
Height. 



V be 



3 « C 
C -= 1* 

c t* E 

> c 

< ^ 



Wood Volume. 



.5 > 



o i^ 



Increment, 



4) 




bc 


n 


05 


3 


V 


c 


> 


a 


<< 



be ! 



Secondary 
Stand. 



Wood 

and 
Brush- 
wood. 



(b) Staud Descriptions contain: (i) Statements on the condition of the soil (subsoil, 
root space, humus contents, cover) and situation (slope, exposure, etc.). (2) Species, 

mixture The space each species occupies is expressed in decimals. (3) 

Age. Mean, minimum, and maximum age is given. 

The compilation of age classes is given in the age class tables separately for each 



igS American Forest Regulation 

working group .... The areas under regeneration are entered in the column 
"Regeneration Class." The areas are also distributed as accurately as possible in the 
columns: "(old timber," young growth," and "openings or clearings)" (p. 270) .... 

4. Index of Yield. The productivity is shown by: (a) The stand mean; (b) The 
total basal area; (c) The site class. To this must always be added the species to 
which it relates. In mixed stands only the main species is considered; (d) Per cent 
stocked 

5. The Growing Stock; (a) Main Stand .... 

Secondary Staud (Zzinschcnbestand, Nebcnbcstand). This includes .... all sup- 
pressed trees and those that suppress the main stand (therefore to be removed if not 
resulting in undue openings). Secondary stand volumes that probably can not be 
utilized in the coming decade, are not given in the estimates. 

6. Mean Increment at Probable Felling Age .... uncertain plantations are 
omitted 



7. The Volume Increment Per Cent, calculated according to the formula i 



(200 \ 
"^7 



"^ ^ M and m = volumes n years apart. The volume and increment calculations 



M+m 

in young and medium aged forests are as a rule from yield tables; in nearly mature 
and mature stands, on the contrary, an accurate calculation of the growing stock is 
always made. Unevenly stocked areas less than 5 acres in area, are com- 
pletely calipered. In regular stands sample plots (5-10% of the stand area) are selected 
in suitable locations (p. 271). The volume calculation is based on mean trees .... 
All volume and increment figures are compiled and appended to the working plan. 

(20o\ /20— q\ 
— II I 

in which Q — q = average net difference of value, Q + q = the sum of values of the 
average cubic meter . . . ., n = the number of years which the stem requires to grow 
from one class to another. 

9. The Index Per Cent (after Pressler) calculated according to the formula: 

W =: (a — b), where a = volume per cent, b =; value per cent, H = the average 

H-hG 

value of the stand, G = base capital (soil, administration and forestation capital . . .). 

ID. Notes on the Management of the Stand (time and method of utilization, cleaning, 
thinning, pruning, reforestation, drainage, etc.). 

General Description. This records the current natural, legal, political, technical, 
commercial, financial and organization conditions, and includes especially: the area of 
the administrative unit (separated into forest and non-forest soil), how the non-forest 
soil will be used, .... property and legal conditions, boundaries, agricultural uses, 
water conditions, topography and soil, situation, climate, atmospheric influences, stand 
conditions, their history and management up to date, timber volume and money yield, 
secondary uses, hunting and fishing, timber prices in the forest and at the market, 
statements regarding personnel, etc. 

3. Determination of the Felling Budget. This is given for a decade. The product 
is classified as main fellings, intermediary fellings and accident fellings. 

All yields, (p. 272) from the felling areas (selected for the next management period) 
belong to the main cut, as well as those accidental fellings that necessitate reforestation 
on at least .8 acre. Timber from windfall, snowbreak, frost or insect damage, and 
stolen timber recovered are entered separately as accidental fellings. The yield from 
weedings, thinnings and other improvement fellings .... are classed as secondary 
fellings. 

(a) Main Felling. The normal felling area forms the basis for the allotment to the 
next management period .... The determination of the rotation .... is based on 
the following policy: If there are no forceful reasons (due to transportation conditions 
or market) for the retention of the present rotation (especially if very high), the new 



Appendix 199 

rotation should aim at securing an adequate interest rate on the capital investment. 
Those stands are considered mature where the index per cent has sunk below the 
current rate of interest (provided fellings are possible, with due regard to the rigid 
demands of the felling series). 

Unquestionably the following stands must be alloted (for utilization) to the next 
period: necessary severance fellings, safety strips, irregular stands with low increment 
(whose speedy regeneration is desirable because of low increment and poor soil con- 
ditions), and finally those stands which must be sacrificed to obtain a proper felling 
series. In irregular stands the felling areas are to be corrected .... The Instruc- 
tions prescribe: "In determining the main yield in the annual management plan for 
each working group, on the basis of the age class table, it must be stated whether 
mature stands or stands capable of being cut and younger age classes (to be cut later) 
are sufiicient, whether the cutting of mature growing stock is to be curtailed (and if 
so for how long), or whether, on the basis of general management rules a more rapid 
utilization of any existing volume surplus is desirable or justified (p. 273). "The time 
in which the creation of the normal age classes is to be attempted, is to be based on 
expert advice. The budget justifies the determination of the normal felling area by a 
summary of past fellings and the influence which these fellings have had on the 
development of the age classes. The age class conditions are therefore shown for a 
considerable period." "These comparisons and considerations," say the Instructions 
at the close of this section, "will lead to a final determination of the felling area; and 
the calculated volume (increased by the current mean increment up to the m.iddle of 
the period of management), forms the volume budget for the decade. The strictly 
sustained yield is not necessary for each working group, except in those forests which 
are heavily burdened with servitudes. 

(b) Secondary and Accidental Fellings. Secondary fellings are classified as cleanings, 
weedings, thinnings, and fellings of seed trees* in young stands. The secondary fellings 
budget is found by summing up the proper merchantable volumes (estimated for each 
lot in the stand descriptions ....). The estimate for accidental fellings for each 
working group is summarized according to the records of past years, or according to 
experience. 

(c) Estimate of Yield in Selection Forests. Since the selection forest aims primarily 
at the protection of the soil, and since a regular sale of the cut is frequently unfeasible, 
the determination of a sustained yield budget (according to the definite established 
method) is usually given up and the felling budget is estimated by judgment. 

4. Control and Revision. To show the changes which have taken place in the course 
of the management period, a number of records are kept by the administration; these 
control the estimates of the working plan and its execution, and serve as a basis for 
future revisions. Of special importance is: 

(a) The Journal (p. 274) which is similar to the general part of the Prussian ledger 
(Hauptmerkbuch). In it, are recorded: all changes .... occasioned by fellings 
.... contrary .... to plans, changes in area or boundaries, in transportation and 
communication, important injuries by man, natural phenomena, fires, etc.; also state- 
ments about hunting and fishing, labor conditions, statistics regarding volume and 
financial results, works for the control of torrents, forest experiments, personnel, etc. 

(b) The Management Book (like the Prussian Control Book and the special part of 
the ledger) is divided into two parts. The first gives for every single lot (Kontroll- 
figur) the cut of material in round numbers (divided into timber and fuel wood, hard 
and soft wood, main, secondary and accidental fellings) together with the respective 
felling areas; also the reforestation carried out (divided into sowing and planting) as 
well as drainage data and the care of the felling areas and stands. The second part 



* So called "overholders" are not misshapen trees stealing light and food from the 
main crop but instead are trees held over from the former crop to furnish seed. 



I 

200 American I'orcst Regulation 

contains the annual compilation of fellings from the whole administrative district and 
the check of fellings (actually cut) together with their estimates. 

(c) Statistics concerning: changes in ownership, cut of stands (compared with the 
estimate), fellings (compared with the volume and area given in the felling budget) 
not prescribed in the plan, forestation and cost, income and expenditures, material and 
money results, etc. 

There are 2 kinds of revisions: (i) intermediate revisions, which become necessary 
in the course of the management period, due to unforeseen conditions (windfall, injuries 
by insects, etc., and (2) regular periodic revisions, which are undertaken the last year 
of the decade (for which the working plan was drawn up). The most important 
problems of the periodic revision are: In the first place an investigation as to whether 
the working plans have been closely adhered to in all parts, whether and to what 
extent the deviations have been justified, and how far the regulations of the old working 
plan have been proven correct in detail and as a whole. Secondly, the correction of 
the existing geodetic and mensuration data (or such new data as may be required for 
the next decade's working plan). Thirdly, the preparation of the working plan for the 
next decade (p. 275). The intensiveness of the revisions depends on local conditions, 
but as a general rule the work must be done according to the "Instructions for New 
Forest Organization." 

X. FRANCE. 
See "Studies in French Forestry," by Theodore S. Woolsey, Jr., John Wiley & Sons, 
1921, pages 206-261, 469-495, and 500-534, for a discussion of regulation in France. 

APPENDIX A. (b) FINANCIAL ROTATIONS (FROM ENDRES). 

A. Concept and Reckoning. By financial rotation we understand that period 
which, according to the soil rent theory, will produce the greatest land rental. It therefore 
falls at the time when the proceeds from the land are greatest. 

a. The financial rotation of single stands. If the stands are normal one reckons 
the soil rent for the several age classes (considering together those having similar 
earnings and cost) and the financial rotation is fixed at that age which indicates the 
greatest land returns. If it is a case of fixing the rotation for a stand not yet planted 
then one has to have interest tables to guide him in the work of fixing the rotation 
period. 

It is obvious that the rotation period found in this manner is valid only so long as 
those data, which has been used to figure out the rotation, remains unchanged. Each 
permanent change of these conditions also causes a change of financial rotation. 

Since there is no cost of administration and management the cost is very small and 
owing to the fact that it would have a long drawn out effect upon the final interest, it 
suffices to state, for the final rotation, the following formula: 

_ Au plus Da I, o p" — a plus 

R" - I, Op« — I 

Where B = Capital land value. 
A = Yield. 

D ^= Value from thinnings. 
u = Years in rotation, 
a =Time of thinnings. 
Or, when the thinnings that have been computed ahead are expressed as a per cent 
of the yield, we have 

Au . i.od 



Bu: 



I. Opu — I 



The financial rotation or better still the rotation in abnorjiial sta)ids is arrived at. 

(a) Through figuring the largest future return. 

(b) Through figuring the growth per cent. 



Appendix 201 

In both cases we consider the maximum normal use of the forest soil for continual 
use. If we contemplate putting the soil to other uses such as farms or sale then we 
must figure in the higher value. 

This formula could also be used to figure future value of normal stands. The largest 
future stand value of normal stands is figured on that rotation in which the soil rent 
culmination and the per cent earned will at the same time be equal to the rate of 
interest. 

Owing to its simplicity the growth per cent is used in preference to the method of 
largest future returns. 



b. The financial rotation of the zvorking circle. In order to approximate the area on 
which money returns will be forthcoming yearly, and to make sure of the area to be 
thinned the forest working plan must set forth some definite time limit as a working 
basis, that will suffice for the timely or orderly use. This time limit will serve a 
general rotation period of the working circle. 

Because the largest forest is never made up of equal working stands it is impossible 
to figure rotation by a mathematical formula. It is more likely to be the' average 
financial rotation of all single stands, from which again the older marketable wood 
must be given primary consideration. 

We cannot measure the influence which the general rotation will have on the single 
stands. We cannot characterize it as Kraft has done. 

The length of the general rotation is influenced by the financial working of the single 
stands. The financial producing power of the stand depends on the manner of handling. 

It does not all depend on whether the stand has a general rotation that 

is too long or too short; whether the stand is too old or too young; whether or not 
the age of the stand surpasses the general rotation; or whether the stand is growing 
on good agricultural soil. These are all considerations but they do not determine the 
rotation period. It w, moreover, through the use of growth per cent that ive get at the pro- 
ducing pozver and usefulness of the stand. This is arrived at through the measurement of 
the product. All stands that cannot come up to the desired quantity of products should 
not be considered for felling; they deserve consideration on account of their growing 
condition for the building up of a good later cut. 

In normal forests the financial rotation falls at the time when the formula gives a 
maximum result. 
A„ plus Da plus . . . Dq — (c plus uv plus uNO. Op) 

u 
This period of time culminates with the soil rent period, because: 
Au-Da— . . . Dq — (c — uv)— N. O. Op= (Bu plus N) O. Op — N. OOp = Bu 

u 
By N is to be. understood the soil rent value of the figured rotation "u" or, the value 
of the soil under normal conditions. Therefore it is shown that the use of the first 
formula is a roundabout manner of determining the financial rotation; having to figure 
first the soil value for different rotations it is useless to figure financial rotation by 
the first formula. 

In recent times, Martin has used the first formula however with certain changes. He 
used instead of expected value or cost value the value it would have if of actual use. 
This is theoretically unreliable. Nothing is gained thereby from a practical standpoint 
as the determination of the actual value of usefulness of young stands is very difficult 
and, more often, impossible. 

B. The Length of the Financial Rotation. The length of the financial rotation is influ- 
enced by all of the follozinng factors zvhich affect the climax of the soil rent. Of the afore- 
mentioned facts it is important to note (p. 72). Of great influence is the rate of interest 
used. For high interest rates you figure short rotations, for low rates long rotations 



That you exercise care in the general handling and forest management of the two 



202 American Forest Regulation 

categories of soil; — namely, profitable and unprofitable soil. For the question of putting 
through and continuing the financial rotation only the productive soils can be given con- 
sideration as forest soil. 

In soils belonging to the unprofitable category you figure for pure, even-aged, closed 
stands with a working interest of 3% a financial rotation of from 60 to go years. The 
absolute length of the rotation depends principally upon the value of older stands to 
the younger stand. The longer the value continues to increase the longer will be the rotation. 
Of primary importance is the quality increase. Should the quality increase soon cease 
and should it not be possible to continue the quality by clearings and liberation cuttings 
then the rotation will be much lower. 

In dense even-aged stands the finattcial cutting period comes later zvith poorer soil and slozver 
grozvth. In both cases the quality increase of the wood is concentrated on the higher 
stand ages. 

From the measurements by Oberforster Schulze (Allg. Forst und Jagd. Zeit. 1889, 
p. 329) the financial felling age in the Royal State forests using p = 3% is shown in 
the following table: 



Spruce. 



On 



2% of the 


area = 


1,200 ha. i 


n the 55- 60 years 


9% " " 


" = 


5,700 " 


' " 60- 65 


25%- " " 


" = 


16,500 " 


' " 65- 70 " 


21% " " 


" := 


14.300 " 


' " 70- 75 " 


21% " " 


" = 


13,800 " 


" " 75- 80 " 


7% " " 


" = 


4,800 " 


" " 80- 85 " 


11% " " 


" = 


7.300 '■ 


" " 85- 90 " 


2% " " 


" = 


1,500 " 


" " 90- 95 " 


2% " " 


" = 


1,200 " 


" " 100-10- " 



(The highest rotations fall on the ore mountains of Saxony.) 



On 









Pine. 






7% of 


the 


area = 


1,500 ha. 


in the 


50- 55 years 


2o7o " 


" 


" = 


4,400 " 


n a 


55- 60 " 


26% " 


" 


" = 


5,600 " 


" " 


60- 65 


ig7o " 


" 


" =1 


4,000 " 


" " 


65- 70 " 


6% " 


" 


" z= 


1,300 " 


a it 


70- 75 " 


12% " 


" 


" = 


2,600 " 


" " 


75- 80 " 


io7o " 


" 


" ■= 


2,200 " 


" " 


80- 8 s 



For the spruce stands of the Thuringerwalder, Forstmeister Schmidt shows the 
lengthened time of the financial rotation for the different soils, gotten at by figuring 
the growth per cent. Figuring p = 3%, the table shows the following average yield 
per cents: 

for 87-92 year old stands of 



for 95 year old stands on 
for 97-105 year old stands 

for older stands 



II soil 2.74% 

III soil 2.8970 

IV soil 3-287o 
II soil 2.86% 

IV soil 2.97% 

II soil 2.667o 

III soil 2.57% 

IV soil 3-i47o 
II soil 2.6o7o 

IV soil 2.79% 



Wimmennaurer figured in three different forests of the Grand Duchy Kissen for the 
pine II and III stand classes; rotations from 60-70 years when p = 2.5%. He remarks 
that by introducing liberation cuttings many rotations are reduced from 120 to 100 years. 



8o years 


100 years 


120 years 


$163 


$153 


$131 


104 


93 


76 


68 


58 


46 



Appendix 203 

Oberforster Walter figured, in his forest Grebanare, the following growth per cent 

values for the pine: 

(AUg. Forst unci Jagd., 1888, p. 202.) 
Age 60 years 

for p — 2% $149 

p = 2.5% . 100 

P = 3% 70 

C. Estimating the Financial Rotation. For the unprejudiced forester it is needless 
to say that it is practically impossible to set a definite year for the determination of 

the financial rotation; We can be satisfied if we are able to figure the 

time of cutting within a ten-year period we should not speak of one year 

but of the period of financial cutting 

The computed financial rotation is then an indication which serves to tell the time 
of greatest soil rent according to the given conditions. It indicates a possible point 
but it should not be taken as the only and inflexible program for regulating the growth 
per cent. It endeavors to realize from the soil the measurement of its productiveness 
and to determine the largest obtainable soil rent. The means by which this is secured 
is not only in obtaining and carrying out the financial rotation but in harnessing and 
assessing the productive strength of the forest soil. The proper distribution of species, 
rational systems of management carried to old age, making use of increased growth 
due to light, reproduction, understory, growing valuable species, — these are the means 
which the forester can apply and they must be made use of by him in obtaining the 
highest possible soil rent. (See the work by G. Kraft, dealing with the "Management 
of the Soil's Productive Power," — 1890, also, — "Consideration of Forest Valuation," — 
1887. The fundamentals given there are gold nuggets of the German literature and 
every thinking forester should take them to heart.) 

When the existing stands are not capable of producing a large enough soil rent (or 
w^hen in order to obtain a reasonable soil rent a very short rotation is needed) then 
the means of remedy lie in building up and improving the stand and in part through 
applying modern technique as a guide in selecting certain kinds of species. These 
considerations are more fully brought out in the following viewpoints. 

(a) First consideration for quality are: Clearness of bole, little taper, soundness of 

the wood If stocking was incomplete when the stand was started, if the 

young stand was grazed, if neglected in the thicket or polcv/ood stage, or if damaged 
by atrocious cutting, or abused through unregulated cuttings or thinnings, — these stands 
will show no improvement in stocking and will produce chiefly scrubby, poorly formed, 
branchy and unhealthy trees with excessive taper 

Such stands are not capable of a high soil rent; on the contrary a low rate of 
increase in valuable timber is the result. The sooner we clear off such undesirable 
stands and replace them with more worthy species, — and thereby utilize the full pro- 
ductive power of the soil — the less will be the loss to the forest owner .... (Endres 
now emphasizes the need for raising fiinbcr rather than fuel and poorly shaped poles). 

(h) It must be concluded that spruce and fir are best grown for timber purposes! 
Spruce and fir have their principal use as lumber and dimension stuff. It is now a 
universal fact in the European market that there is no demand for boards wider than 
1 1.4 inches. Squared timbers 13.8 inches in diameter command comparatively low 
prices; sizes larger than this have practically no sale. The average price paid for 
spruce timbers in the Royal-State forests during the ten years 1880-1889 per cubic 



eter: 


— 








Per 1000 


Increase in price 




Average diameter 


Per cu. 


m. 


board feet 


per cu m. 




5-9 


inches 


$2.50 




$10.00 






6.3 to 8.7 


" 


3-07 




12.28 


$0.57 




9 " 1 1-4 


" 


4.02 




16.08 


■95 




1 1.8 '■■ 14.2 


" 


4-6S 




18.60 


.63 




over 14.2 


" 


4-75 




19.00 


.10 



204 American Forest Regulation 

Timbers over 14.2 inches in diameter as compared to those from 11.8 to 14.2 in diameter 
ha\e a quality increase of only $.10 per cubic meter. The largest increase in price lies 
in the timbers between 9. to 1 1.4 inches. 

Regarding the sale of construction timber the conditions are not much different. The 
industries of modern times demand iron for the heavier uses. The buildings that formerly 
used heavy fir timbers for girders now use metal; for other uses, where formerly very 
strong beams were required, they obtain the same strength by joining several pieces together. 
It becomes necessary for the mills to cut out of large logs smaller sized dimension 
timber and boards according to the sizes called for. 

Oberforster Karl observed the same conditions for the Alsace-Lorraine and Klein 
markets. It is interesting to note that the fir (the so called "Holland wood"), which 
was raised purposely in the* Black Forest for heavy timbers no longer is demanded; 

already there is an over-supply 

'"These latter, or so called standard sizes are the most saleable and can be disposed 
of in large quantities. In view of the fact that the increase in groivth of the older trees 
at 120 years will be at the highest only J. 5% and the increase in price from standard grade 
to "Holland wood" (largest size) will be at the most $.25 per cubic meter, it can be 
easily figured what will become of the profits if we raise large sized fir timbers .... 
The practice of growing large timber can only be continued for pine and oak. For 

these timbers you can command a high price and they are sought after But it can 

not be believed that the increase in quality by raising large timber of these species will com- 
pensate for the higher soil charge. In connection with the increase in price that is 
achieved you have a longer producing period to consider. Only in case you can so 
handle the forest through thinnings that the larger timbers are produced in reasonably 
short rotations is the growing of such material possible. It is probably only possible 
on good soils and in connection with a two storied forest. 

(c) Pure beech stands are not suitable for earning reasonable financial returns. 
Up to 1840, pure beecli forests were found in great abundance due, primarily, to its 
prolific natural reproduction. The beech was highly prized for its fuel value and no 
one would have thought that during the development of the railroads and zvithin a ten 
year period coal ivould replace the wood as fuel. The later attempts to encourage the use 
of beech for lumber have been unsuccessful. 

The per cent of lumber produced (by pure beech) is very small, only 20% at the most, 
and then the lumber prices are not much above those received for cord wood. Even 
an exceptionally clear piece of beech lumber will not be worth more than a similar 
sized piece of soft wood. Where the beech thrives best are good sites for softwoods 
and they will give a proportionally larger yield. If softwood is the primary species, 
beech can be grown as an understory and, owing to the beneficial effect on the soil and 
tendencies to cause a better development of the bole in the softwoods and remaining 
hardwoods, it would raise the income of the stand indirectly. 

"In such a practice one should not forget that the beech is used only a^ an improver of 
tJie dominant species zvhich earns the highest soil rent. In other words it is a means to an end. 
Through proper forest management it is possible to restrict its development on its 
natural site 

APPENDIX B. GROWING STOCK AND YIELD, HARVARD FOREST. 
The ascertainment of the annual yield, or total amount of saw timber to be cut 
annually from the Forest was based upon a rough consideration of area, age and 
volume. In the beginning only those stands were reckoned with which contained 50% 
or more of white pine, since hardwood timber was comparatively unprofitable, and 
yield tables applying to it were not available. The rotation and the mean annual 
increment for the whole area were determined from a yield table for white pine made 
by L. Margolin and published by the New Hampshire Forest Commission in 1906. 
Since quality increment in most of the pure pine type is unimportant, the rotation for 
the bulk of the Forest was fi.xed at 60 years which is not far from the point where the 



Appendix 205 

mean annual growth in volume culminates. For arriving at the amount of the annual 
cut, the preliminary field v^'ork supplied the following data: a total stand of saw timber 
amounting to 10,500,000 ft.; a tabulation of areas according to type and age. Being 
almost wholly second growth the stand was everywhere classifiable into blocks of 
uniform age. The growing stock could thus be summarized in three periods of twenty 
years each covering the duration of the rotation. The mean annual increment, as 
derived from the yield table, was found to be approximately 250,000 ft. From the 
summary according to age and area, it was possible to determine in which periods of 
the rotation, as compared with the normal representation of age classes, the growing 
stock was deficient and by how much. Considering the total volume of the stand and 
the surplus of volume in the third period, the theoretical allowable annual cut would 
have been about 325,000 ft. On account of the lack of tried silvicultural methods and 
the need of a good reserve of sizable timber for future scientific purposes, it was decided 
to put the annual cut at the conservative figure of 250,000 ft. or the annual increment 
of the pine-bearing lands of the forest. The succeeding cuttings in mature timber have 
been kept for ten years at this figure and a total of 2,500,000 ft. of lumber have been 
marketed. A reassessment of the growir.g stock and increment was undertaken in 1919. 
As a consequence of the absolute increase in productive forest area due to the planting 
of blank land and to release cuttings, and due to the inclusion of hardwood stands now 
merchantable but omitted in the first computation, the annual increment, exclusive of 
cordwood, is now found to be 38o,0'X> board feet and the total volume of the growing 
stock 12.435,000 board feet. For additional data see Harvard Forest Bulletin No. i, 1921. 



APPENDIX C. EXAMPLE OF A PRELIMINARY POLICY STATEMENT FOR 

INYO NATIONAL FOREST. 

The following is a discussion of existing conditions and the future timber policy of the 
Inyo: 

Dependency and Local Demand: In the absence of transmountain transportation against 
which the high Sierras would seem to constitute a permanent barrier, the only local 
timber supply available for Owens Valley and vicinity is embraced in the Inyo (Mono 
Mills Block of the Mono National Forest). 

The dependency area is defined as Owens Valley north of Owens Lake, Deep Spring 
and Fish Lake Valleys, and the mining camps in Nevada north to and including the 
mining camp of Candelaria. The bulk of the population of this area is located in the 
northern part of Owens Valley in the vicinity of Bishop and Big Pine, Bishop being 
the logical center for manufacture and distribution. The Southern Pacific narrow gauge 
railroad would make possible distribution to the entire .population with the exception 
of a few ranchers in Fish Lake Valley and Deep Spring Valley. The dependency area 
has a population of 5.550 people with a present annual use of 4.000 M ft. of sawed 
material and 3,000 cords of fuel, fence posts and other similar cord materials. All cord 
material and approximately 15% of 600 M ft. B. M. of sawed material was supplied from 
the Forest, the remaining 3,400 M ft. B. M. sawed material being supplied from shipped 
in products largely from the Truckee region. 

No material increases in the use of cord material is anticipated in the near future. 
The Southern Pacific Co. is contemplating standard gauging the present narrow gauge 
road through Owens Valley, which would probably lead to cheaper coal, with the 
result that less wood would be used as fuel, which decrease would probably in a short 
period of years be compensated for by the increased demand due to increase in 
population, further division of ranch property, etc. 

The present demand for building material will probably remain more or less constant 
for a number of years. There is, however, a rapid development in the fruit industry 
apparent in the near future which will probably increase the demand by some two 
million feet of box material within the next fifteen to twenty years. According to 



2o6 Aiiicricaii Forest Regulation 

figures obtained from Mr. Dixon, County Horticulturist, the present use and increase 
for the next five years will be as follows: 

Boxes of fruit shipped during 1920 (all fruits) 3S.000 boxes 

Estimated for 1923 " " 200,000 " 

Estimated for 1925 " " 300,000 " 

Also the shipment of honey from the Valley during 1920 required 10,000 boxes, making 
a total requirement for 1925 of at least 310.000 boxes, which it is estimated would require 
about 2,000 M ft. B. M. of box material in the rough. 

When taken into consideration that the available stand of timber runs at least 50% 
of box and shop grades, this rapidly growing demand for box material is very fortunate 
as making possible practically 100% utilization of the entire product, a large per cent 
of which could not otherwise be utilized locally. In view of the above statements, it 
would appear that the local demand for lumber products within the dependent area 
would be increased to at least 7,000,000 ft. within the next twenty years, possibly con- 
suming that much as an average for the period. 

Available Supply of Commerciai Saiv Timber: The supply of commercial saw timber is 
confined to the northern portion of the Forest, the Casa Diablo block, the Mammoth 
and Summit blocks; the total stand according to cruise of 1907 by Mr. Eldridge is 
670,000 M ft. B. M. 

Timber cut during the past season showed an average age of approximately 130 
years, which if taken as a basis of rotation would indicate that the local demand 
would exceed the annual yield of the available stand within the next twenty years. 

Condition and Accessibility: The entire stand of timber is largely mature, the Mam- 
moth Block particularly being over-mature as indicated by flat and spike tops and 
other indications common in an aged stand. Also this block shows unmistakable 
indications of a more or less general insect infestation. (Dendroctonus, according to 
reports by Mr. Hopping.) The only sawmill on the Forest is also located at the south 
edge of this block, being operated during the past summer to the extent of 622,000 
board feet cut. The State Highway, which has been greatly improved during the past 
few years, connects this block of timber with Bishop, the distance being 48 miles from 
Bishop to the present plant. The Casa Diablo block is approximately 20 miles nearer 
to Bishop than the Mammoth block, but besides being a much younger, more thrifty 
stand which should not be cut at the present, is also shorter, poorer grade timber 
and though a shorter distance from market, the road is such that it is doubtful if 
transportation costs would be less than from the Mammoth block. Several attempts 
to market local lumber in competition with shipped in products were made prior to 1912. 
that season apparently being the last attempt, which was by the Home Lumber 
Company. The reason for this seems to have been due to three factors: 

1. There was no market for box grades and no means provided for their manu- 
facture. 

2. Road conditions were extremely unfavorable as compared with present condi- 
tions and the motor truck as a means of transportation had not at that time developed 
to any extent, making its use impracticable. 

3. The low prices of lumber prevailing at the time. 

Present operators, F. M. and A. W. Hess, fully recognize the fact that to market 
their production, which is 50% box and shop grades, it will be necessary to provide 
means of manufacture in order to market those grades at a profit. The transportation 
problem has been greatly reduced through improvement of the road by the State, and 
the development of the motor truck as a means of transportation, and it is figured by 
Hess Brothers from the past season's experience that it will cost approximately $10.00 
per thousand under present conditions, as cost of trucks and operating expense, to 
freight their product from the mill to the Bishop yard. Also the present price for 
lumber would justify a much greater expenditure to place the lumber on the market 
than was the case at the time the Home Lumber Company failed. 



Appendix 207 

Sale Policy: i. In recognition of the fact that Owens Valley and adjacent community 
must eventually be entirely dependent on the timber within the Forest for a local 
lumber supply, no timber should be sold in the future that will allow exportation 
beyond the limits of the dependent community. 

2. The Mammoth block of timber showing signs of disease and insect infestation, 
besides being equally as accessible as any other block of saw timber, should be cut first 
and sales for the time being confined to this block. 

3. The main object of our whole sales policy should be to build up a local lumbering 
industry that will eventually supply the needs of Owens Valley to the fullest extent 
possible from the local product without exceeding the annual yield of the available 
stand, which, exclusive of the Mono Mills block of the Mono Forest, would be approxi- 
mately 5.000 M ft. B. M. of an annual cut. 

The project is too small to hope to interest large lumbermen and must, therefore, 
in all probability start in a small way from local capital and build more or less gradually 
against strong competition from the outside, which at present controls the market. 
Therefore in order to assist the local operator to meet outside competition, which may 
or may not be based on the cost of production but rather with a view of eliminating 
the local operator, such sales as would tend to create competition in the manufacture 
of the local products should be discouraged until the local product has reached the 
proportions of an industry and established its market. Until such times as the local 
industry will have established itself there can be no necessity for limiting the selling 
price of the local operator when we cannot limit the selling price of the shipped in 
product in case the local operator is forced out of business. At such time as the local 
industrj^ has firmly established itself we should then undertake regulation of selling 
price based on cost of production as we would have by that time sufficient information 
on the cost of production on which to base a fair selling price. 

4. Our minimum annual cut required by contract has, it seems, in some cases, forced 
a local operator into bankruptcy, due to the fact that his competitors lowered the price 
of lumber to the extent that he could not market his production at a profit, his finances 
being limited, and our minimum cut requirement forcing him to operate at a loss. 
Therefore, for the time being at least, we should place our minimum annual cut at a 
very low figure, and if necessary, waive it entirely if it will assist the local operator in 
his fight to continue his business. 

5. There is no question but that the present stumpage price of $2.50 a thousand for 
yellow pine and $1.50 a thousand for fir both red and white does not represent the 
full stumpage value of the timber, but in order to assist the local operator to meet 
competition from the outside, I do not believe this price should be raised until such 
time as the local operation has shown that to raise the stumpage price will not eliminate 
the operation entirely. 

Timber Needed for Forest Development: All timber within the headwaters of Pine 
Creek, Bishop Creek, Rock Creek and north from Rock Creek to Mammoth Mountain, 
lying on the slope of the main Sierras, should be withheld from sale, commercial or 
otherwise, except for use within the area involved. This area has a very light stand 
of timber and great value for power development, irrigation, storage and recreation 
and it is practically certain that all of the timber within this area will be needed for its 
development. 

Supply of Fuel, Fence Posts, and Similar Material: The present population of Owens 
Valley and almost the entire population dependent on the Inyo Forest for fuel, fence 
posts, and other similar materials, is located between Manzanar and Chalfant (see 
map). That portion of the Forest bordering the Valley on either side emliraces a 
sufficient stand of timber to supply all future needs for cord material. 

The best estimate of this timber being that given in connection with land classifi- 
cation, and which places it at some 380,000 cords, which is api)roximately 80% Pinon 
pine, 15% Foxtail pine and 5% other species. Taking into consideration present use 
and possible future development of both community and Forest, and the administration 



2o8 American Forest Regulation 

of the Forest, the source of supply and the community are divided into three separate 
units of supply and dependency. This division is thought advisable for three reasons: 

1. To prevent overcutting by the community as a vi^hole within the area on which 
a portion of the community is logically most .directly dependent, and thereby necessi- 
tating in later years, back haul of the same material. 

2. Wagon roads and other means of access will be necessary in the near future 
in order to obtain fuel and post timber. To get the necessary improvements and to 
properly distribute the cost of same, it is thought that some form of organization will 
be necessary, and to reduce the size of the community to be dealt with in each case, 
and to properly assure them that what they develop will be available only for a limited 
community, will make it comparatively easy to promote the necessary development. 

3. In the proposed division, one or more units in the dependency and use conform 
to administrative districts which gives the ranger the advantage of knowing his users 
and the opportunity by assisting them in a plan of development, to group his cutting 
instead of having them scattered as at present throughout the district. 

In making these divisions, the pains was taken to obtain sufficient information regard- 
ing population and use of material by the different communities, to make sure that each 
community would be supplied indefinitely with timber suitable for fuel and ranch 
development; the amount of timber and population in each unit being as follows: 

Area No. i, or the Aberdeen Independence area: Has a population of 1,100 people 
with a wood supply provided of 88,882 cords. 

Area No. 2, Big Pine-Tinnemaha area: Has a population of 1,200 people, 121,362 
cords. 

Area No. 3, population of 3,256 people, has a timber supply of 168,469 cords. 

It is planned to confine both free use and sale of all cord materials within each 
community to the area on which that community is logically dependent, as outlined on 
the map. 

P'ree use will be issued only for dead, insect infested timber. 

Commercial sales to be made in any quantity, but only for delivery within the 
community. 

S-22 sales will be issued for both dead and green material, being limited as near as 
consistent with the law under which these sales are made, to dead, diseased and insect 
infested timber. 

There is at present no large demand for S-22 sales outside of the dependency areas 
as outlined, and we shall endeavor to confine sales of this nature to these areas. 

Very truly yours, 

(Signed) T. J. JONES, 

Forest Supervisor. 

December 14, 1920. 



APPENDIX D. RESULTS OBTAINED BY FRENCH WORKING PLANS IN 

SAVOIE FROM ORIGINAL FIGURES SUPPLIED BY A. SCHAEFFER 

(CONSERVATEUR, SERVICE DES EAUX ET FORETS). 

* The recovery which this region has made under French forest management is a 
lasting tribute to the foresters of the Republic. This region was only ceded by Italy 
in i860, and prior to that date the forest had been overcut and damaged, the prices 
were low, and there was a large amount of overmature diseased timber. A. SchaefTer, 
for many years chief of working plans, with headquarters at Grenoble, has studied the 
rotation, cutting period, stand per hectare, increment, and financial yield before and 
after past working plan revisions, and has proved that the conservative management 



See pages 37-38, "Studies in French Forestry," John Wiley & Sons. 



: HECTARE 
meters) 
NAME OF THE FOREST Beginning of the present rotation 
(All selection fellings) Average Old 



Nancy sur Cluses (ist W. G. 

Habere Lullin 

Thones Ville 

Vigny Matlioncx (2d W. G.) 



Vercland (ist W. G.) 

Average (fractions omitted 



Luzier 

Petit Bornand (istW. G. (pic) 

St. Paul 

Rognaix 

Montgilbert 

Average ( fractions omitted 

Bourg St. Maurice (ist W. G. 

Macot (ist W. G.) 

do (2d W. G.) 

Villaroger (3d W. G.) 

Average ( fractions omitted 

Ito Foy (2d W. G.) . 

do (3d W. G.) . 

do (5th W. G.) 

Tignes (3d W. G.) . 

Val d'Isere (3d W. G.) 

Villaroger (ist W. G.) 

Average (fractions omitted 



timber 


timber 


Total 




FIVE FIRST CLA 


174 


276 


450 


180 


154 


334 


187 


303 


490 


54 


474 


528 


99 


200 


299 


138+ 


231 + 


420 



96 

102 
118 
136 

93 
109 

160 
IS6 
156 

150 
155 

73 



FIVE SECOND CL 
158 254 



88 


190 


83 


201 


123 


259 


155 


248 


121 


230 


FOUR THIRD CL 


94 


254 


60 


216 


52 


208 


U7 


287 


86 


241 



SIX FOURTH CL/ 
92 165 



100 


63 


163 


93 


34 


127 


48 


58 


106 


31 


7 


38 


79 


77 


156 


71 


55 


126 



Appendix 209 

introduced by the French is successful. These forests, classed according to yield pro- 
duction, may be grouped in four classes: 

1. Those forests with a yield of over 6 cubic meters (21 1.9 cubic feet) per hectare 
(2.5 acres) per year. These are found on the sandstones, schists, warm calcareous soils, 
and alluvial soils near the lakes of Geneva, Annecy, and Bourget. Such yields are 
almost comparable with the famous Jura and Vosges. 

2. The second- and third-class forests are yields between 4 and 6 meters (141. 3 and 
21 1.9 cubic feet) and between 3, 4, and 2 meters (141.3 and 70.6 cubic feet) respectively. 
Here, either the soil or the climatic conditions are naturally poor producers. Some- 
times this intermediate yield is due to the mediocre combination of both climate and 
soil. 

4, The fourth class of forests is where the production is less than 2 cubic meters 
(70.6 cubic feet) per hectare (2.5 acres) per year. These are located in the high valleys 
or rocky slopes where the climate is severe or relatively dry. 

The table: Results of Forestry Management in Savoie, France, faces this page. 

From a study of these figures the following conclusions can be made: 
(i) *Under the fairly intensive conditions existing in Savoie the area of the work- 
ing group increases with poorer soil conditions, except that towards the limit of tree 
growth the groups are small including only the slow growing Alpine forests. 

(2) After the rotations are once correctly established there is little or no change. 
The length of the rotation increases with poorer soil quality. 

(3) Without changes in local conditions the cutting cycles tend to remain the same. 

(4) With forest management there is a tendency (in France) to increase the 
growing stock and with selection forests it is essential to have a mathematical check 
on the marking. With the French method of 1883 the average timber should be ^ 
and the old timber ^s the total volume. This is empirically true, so if at the revision 
of a working plan, it appears that the proportion is not being maintained this fact 
should influence the marking during the next cutting cycle. This also illustrates the 
necessity in selection forests of not cutting to a strict diameter limit, but rather according 
to the needs of the stand as a zvhole. It is also necessary to have in mind an empirically 
normal selection stand per acre to steer by before attempting to mark the stand. 

(5) The present current yield is a useful check on the yield allowed; the relation 
between the current increment and the yield is tiever a fixed ratio unless the forest is 
normal. 

(6) With wise forest management there is usually increased yield until the abnormal 
forest becomes more nearly normal but the silvicultural condition of the stand often 
precludes too rapid an economy in growing stock. 

(7) With wise forest management the money yield is constantly increasing; and 
with the gradual increase in stumpage prices which is going on all over the world (and 
with the diminishing value of money) this increase will probably never cease if there 
is continued and wise management. This is one of the greatest arguments for forestry 
as a conservative investment where there is certain protection and permanent (public) 
ownership. 

(8) As would be expected the expenses diminish with the less valuable soils but 
not in the ratio of diminished revenue. 

(9) A change in the proportion of the species in a selection forest under natural 
regeneration is slow and difficult without artificial assistance. This indicates how 
futile it is for management officers to plan sweeping changes in species ratio without 
figuring the cost of planting or sowing — unless a radical and perhaps dangerous change 
in management is contemplated. 

(10) After a term of years the effect of correct forest management on an under- 
stocked forest is very similar to the increase in capital assets of an industrial enterprise 



*The paragraph numbers refer to the column numbers of the foregoing table. 



(I) 

AREA 

NAME OF THE FOREST 
(All selection fellings) 

Hectares 

Nancy sur Cluses (1st W. G.) 121 

Habere Lullin ^ 

Thones Ville <'4 

Vigny Mathonex (2d W. G.) . }2 

Vercland (1st W. G.) "73 

Average (fractions omitted) 96 

Lmier ^ 

PcUtBornand(lstW.G.(pic)) I37 

Sl Paul +28 

Rognaix 74 

Montgilberl 21 1 

Average (fractions omitted) 177 

Bourg St. Maurice (ISIWG.) 284 

Macol (1st W. G.) 3Sl6 

do (2d W. G.) 200 



(2) 

ROTATION 

(Years) 



Villaroger (3d W. G.) 

Average (fractions omitted) 

llo Foy (2d W. G.) 

do (3d W. G.) . 
do (5U1 W. G.) 

Tignes (3d W. G.) . 

Val d'lsire (3d W. G.) 

Villaroger (1st W. G.) 
Average (fractions 01 



Beginning of the former 1 



Former 


Present 


Average 
timber 


Old 
timber 


Total 


Average 
timber 


18 


18 


ig8 


2U7 


405 


174 


16 


16 


142 


81 


223 


180 


16 


16 


211 


229 


440 


■ 87 


18 


18 


60 


340 


406 


54 


18 


18 


82 


142 


224 


99 


17 


■7 


140 


200 


340 


■38+ 


20 


20 


81 


"7 


■ 98 


96 


16 


16 


(12 


83 


145 


,02 


20 


^ 


87 


48 


135 


118 


[8 


18 


74 


67 


141 


136 


16 


16 


58 


124 


182 


93 


18 


iS 


'^ 


88 


160 


109 


18 


18 


176 


60 


236 


.60 


18 


18 


143 


34 


■ 77 


■ 56 


18 


18 


1+2 


30 


.72 


156 


■5 


'5 


149 


123 


272 


150 


17 


'7 


■52+ 


61 + 


214 


■55 


20 


20 


63 


97 


160 


73 


20 


20 


105 


S8 


163 


100 


20 


20 


80 


30 


,10 


93 


20 


20 


38 


39 
4 


77 
26 


48 
31 


■ 5 


■S 


83 


60 


143 


79 


19 


19 


65 


48 


113 


71 



YIELD 

iters) Present (Cubic meter 

Beginning of the present rotation Increment 
Old per hectare 

timber Total (cu. meters) Former Pt 

FIVE FIRST CLASS FORESTS 
276 450 6.2 3,08 



231+ 420 7.6 

FIVE SECOND CLASS FORESTS 



FOUR THIRD CLASS FORESTS 



SIX FOURTH CLASS FORESTS 
92 165 1.9 



Before the revi 
ief Secondary 

lucts products 



MONEY YIELD PER HECTARE 

: revision After th. _ 

Chief Secondary 



products products 



236 
t5.6 
17.6 



Total 
65.0 



EXPENSES PER 

HECTARE 

(Francs) 

Before the After the 



PROPORTION OF SPECIES 



lUrch 



j Larch 
tfpruce 



1 Spruce 
(Larch 



J 10 



(Spruce 
Fir 
Beech 



2IO American Forest Regulation 

which is being continually strengthened by wise administration. Gradually as the 
company retires its indebtedness and expands, the value of the stock doubles or triples. 
Wisely administered forests fatten in the same manner. 



APPENDIX E. EXAMPLES OF YIELD CALCULATIONS FROM NATIONAL 
FOREST MANAGEMENT PLANS, 1921. 

On November 22, 1921, each District Forester of the Forest Service was written to as 
follows: 

"In looking through the literature on working plans I find tliat there is 

a great dearth of material on actual working plans in the United States. The reason 
for this is obvious. If you have any plans in preparation or practically in final form, 
could you send me a sample of the method you used in calculating the yield, citing 
actual figures used? Could you also send me a sample of one of your most interesting 
policy statements where a working plan is not yet required? 

What do you estimate to be the cost per acre of an extensive management plan, 
(A) for field work, including estimates and growth studies, and (B) office work, 
including report, maps, and computations." 

The data received (up to March i, 1922) is listed by districts: 

District I. Missoula. No data received. 

District II. Denver. The usual policy statements are in force and management plans 
are being prepared for the Harney and Black Hills National Forests. 

District III. Albuquerque. "Policy statements have been prepared for most of the 
Forests." The Apache is an example of an extensive timber policy plan. It is divided 
into two parts: (a) South End (chiefly cordwood) and (b) North End (chiefly timber). 

(a) The cordwood policy is to protect water sheds, supply local needs, increase yield 
for Clifton market, protect recreational requirements. Cordwood sales are to be con- 
fined "to dead material until accessible supply is gone." Cutting of green cordwood 
will be on a very conservative basis. Only improvement cuttings will be allowed along 
Clifton-Springerville highway and at recreation areas. 

(b) Irrigation and recreation must be protected and enough timber to supply local 
market must be retained from export sales. Large scale sales will eventually be neces- 
sary to develop timber resources. Western yellow pine will probably be handled on a 
200-year rotation, 100-year cutting cycles, and 70% to 80% of the stand will be removed. 
One hundred million feet in the northwest corner is withheld from sale for 20 years 
for the Apache Lumber Company now operating in bordering territorj^. About two 
billion feet is available for the general market. 

For intensive working plan data see Part II of this volume for details taken from 
the Coconino working plan. 

Costs have averaged .05 for field and .01 for office work. 

District IV. Ogden. Under date of December 2, 1921 the District Forester writes: 
"The supervisors .... have been reading, thinking and talking about forest manage- 
ment for a long time .... A great dearth of usable data on actual regulation . . . 
The ease with which low grade coast timber comes into competition with our local 
supply has prevented exploitation of any but the most accessible stands .... No 
definite results are available to date." Up to now general policy statements have 
filled the need for regulation. 

District V. San Francisco. See appendix C for a complete copy of the Inyo Forest 
Policy statement which is considered one of the best produced by any district in the 
Forest Service. 

The data which follows for the Eastern Larsen Working Circle is from a rough draft 
not yet approved by the Forester. According to the District Forester: "Since our 
basic data is rough, we feel that it is a useless waste of time to make elaborate, detailed, 
technical calculations of yield." The cost of the field work, including growth studies, 



Appendix 211 

was about $.13 per acre with 7/10 of a cent extra for office. The extra cost of manage- 
ment plans (working plans) is estimated at $.02 per acre above "preliminary timber 
survey work" .... The proposed rotation is 120 years, the net area 160,500 acres, 
the total merchantable stand 2,870,000 M feet of which 75% to 80% is cut at the first 
logging. The loss from the decadent trees is considered offset by the growth in 
younger age classes. If the cutting cycle is 60 years, cut = 36 million; if 50 years, 44 
million; if 40 years, 55 million; if 30 years, 73 million. The timber is extremely 
decadent. A 40-year cutting cycle "is about the shortest period of return that would 
assure a sufficient stand to justify profitable logging" .... 

"There are included within the confines of the proposed initial sale area to the Fruit 
Growers the greatest portion of the most decadent stands and also a bodj^ of timber 
that is the most isolated and the poorest in quality of any in the working circle. The 
argument for a rapid cut-over applies more particularly to this area tlian to the 
remainder of the working circle. A suggested compromise would therefore be to make 
an initial sale to the Fruit Growers upon conditions that would apply the conservative 
marking practice that cuts about 80% of the merchantable timber and which would 
allow an average animal cut of 40 to 50 million feet and at the termination of this sale, 
to make a second sale reducing the cut to about 25,000 M feet which would be com- 
parable to a strictly sustained yield. It is believed that this compromise plan adequately 
protects the best interests of the Forest Service and fulfills the primary object of 
management to harmonize best the prescriptions of silviculture, sustained yield, and 
sound economics. I therefore recommend the adoption of this plan." 

District VI. Portland. According to Hanzlik: 

"Thus far in my calculations regarding the sustained yield, I have used what may 
be called arithmetical method, checked by some of the standard formulae. Von Mantel's 
and Hufnagl's coming about the closest, although I consider that both of these give 
too high a cut from our present type of forests in the Douglas fir region. It is difficult 
to explain clearly the arithmetical method used; it is what may be called a "cut-and- 
try" method starting with a cut based on one of the above formula and then carrying 
out through a rotation or two the theoretical stands resulting from a decrease of the 
mature stand and an increase, based on standard yield tables, in the present immature 
stands and the cut-over areas as development proceeds. 

As an illustration, using the North Santiam Working Circle, Von Mantel's formula 

Y =— , we get Y = 4-°°0-°"0 ^ , or Y = 100,000 M feet B. M., basing the cut on a stand 

VzT 40 

of 4 billion feet and an 80-year rotation. 

Hufnagl's formula takes into consideration the increment from the immature timber, 
and in this case we have the following to start with: V = 4,000,000 feet B. M. (mature 
volume). Immature growth: 

31,000 acres 80 years old. 
6,000 " 40 " " 
38.000 " 10 " 

The increment for this circle is based on Site II, Douglas fir yield tables, and is esti- 
mated as being 60% stocked when compared to the stocking from which the Standard 
tables were constructed. It is obtained by a summation of the increments of the 
various immature age classes taken at one-half the rotation period, thus: 

Present Age Area M. A. I. 40 yrs. hence* Total M. A. I. 40 years 

Years Acres feet B. M. per acre hence — M. feet B. M. 

10 38,000 258 9,800 

40 6,000 375 2,200 

80 31,000 404 12,500 

Substituting in Hufnagl's formula: 

V-Ldx'') 4.000,000 M -I- 24,500 M X ^° 

Y — ^ Y - = 

L §? 

2 2 

4.0 00.000 M -f (24,500 M X 20) _ 4.490,000 M _ J J 2,250 M ft. B. M. 
40 40 

The yields, Y, as obtained by these formulae are used only as an indicative factor 



* Based on Site II, Douglas fir yield tables, present immature stands stocked 60% 
of standard stocking. 



212 American Forest Regulation 

4 

whereby the recommended yield is finally determined, this final yield being made by 
the arithmetical method as mentioned previously." 

Costs have depended on the amount of intensive estimating (lo cents per acre), but 
the district plans to keep v^^orking plans simple and inexpensive. The Row River 
Plan will cost 7/10 cents per acre. 

District VII. Washington, D. C. No data received. 



APPENDIX F. COMMENT ON WOLFF FORMULA. 

The above graph* is based on the figures of table 0. This is intended to depict the 

distribution in volume on 60 acres based on a 60-year rotation, to obtain a normal 

stock with the yields for each period. Up to the age 20, at which the first yield figure 

is given, the growth has been a straight line from the age zero. Then by the yield 

table method, the normal stock would equal in volume the shaded portion comprising 

the polygon A-B-C-D-E-F-L-G. The triangle A-O-G is necessarily omitted since the 

growth that it represents cannot be estimated. To make the yield table method com- 

• - IXR 
parable to the original unmodified method of obtaining normal stock, this triangle 

would in theory have to be included. Now by Moore's method, the normal stock 
obtained would be included in the triangle G-F-L. The area therein included happens 
to be fairly close to that of the polygon above described, since the portions of the 
shaded area above the line G-F are almost great enough to balance the unshaded 
portions included below the line G-F. 

On the other hand, by Wolff's formula, the area included is the trapezoid A-F-L-G. 
Here the growth is a straight line between A-F, as is the case in Moore's formula 
between G-F. It is patent, in this case, that there is vastly more of the unshaded 
portion included than there is excluded of the shaded portions; also, that the result 
would be still more in excess of the yield table method than Moore's formula gives. 

Comparisons of the three methods will likely yield similar relative positions when 
the mean annual growth before rotation age is less than at rotation age, especially if 
the mean annual growth is constantly increasing to a maximum at the rotation age 
(giving a "concave" curve) and where the age, as in the example given, is very low. 

While neither Moore's nor Wolff's formula gives the correct figure (as determined 
by the yield table) the method suggested by Wolff is mathematically the most correct. 

It will be found that the nearer the "estimateable" age approaches the rotation age, 

the closer will be the results by the Wolff formula to those of the yield table method 

and the further away the results by the Moore formula. Vice-versa, the younger the 

"estimateable" age or the further away from the rotation age, the more closely will 

the results by the Moore formula and the yield table method approach, and in fact the 

I XR 
more accurate will tend to be the original — — method of obtaining the normal stock. 

2 

As pointed out, if the lineaments of the yield curve change, — a not improbable possi- 
bility, — these relations will change. The Wolff formula will usually give the best 
figures because when approximating the curve by a straight line, the Wolff method is 
mathematically correct and the Moore formula is mathematically wrong. 



* See page 63 for this graph kindly supplied and discussed by Wolff. It was learned 
after this text was set up that H. H. Chapman had lectured on this problem as earlj^ as 
1909, but had never published. 



INDEX. 



Age classes in regTjlation, 56,* loi, 124, 131, 
151- 153, 157, 160, 166 

averages, 154 

immature, etc., 157 

in selection forest, 124, 160 

table of, in Kingdom of Saxony, 184 

table of, in Prussia, 177 
Albuquerque, 210 
Allen, E. T., 46 
Allotment methods, defined, 91 

by area, 91 

by area-volume, 93 

by volume, 93 

compared with stand method, 100 

principles, 94, 114 
Alsace-Lorraine, 194, 204 
Amenagement (see working plans in France) 
American method, determination of cut bj'^ 
(Part II, see also regulation, and 
cutting cycles), 105 
Annual cut (see regulation) 
Annual plans, 5 
Apache, forest poHc}' of, 210 
Appendix, 175 
Area, determination of cut by (see fixed 

area, and allotment by area) 
Area-volume allotment, differs from stand 

method, 100 
Ash, 48, 49 

Ashe, W. W., 32, 43, 47 
Attitude of private owners, 105 
Austrian formula, determination of cut by, 
72, 79, 80 

illustration, 82 

summary, 81 
Baur, 35 

Biolley, H. E., 29, 69, 78 
Blackjack (see western yellow pine) 
Blascheck, A. D., 30 

Block (see also management subdivisions), 
defined, 24 

discussed, 25 
Brandis method (see Indian method), 86 
Breymann's method, determination of cut 

by. 7'^, 80 
British India, 5 
Bureau of Forestry, 6 
Capital, definition of kinds of, 39 
Carter, C. E., preface 
Chamnnix working plan, 30. 85 
Chapman, H. H., author of Part II, preface. 
105 

references to works of, 5, 34, 2)7, 126, 151, 
152, 212 
Chapman, C. S.. 16 
Chestnut, 34 
Coconino forest working plan, 102, 128, 157, 

160, 210 
Compartment (see management subdivi- 
sion), defined, 24 

discussed, 25 

• The numbers refer to pages and not to para- 
graphs. 



Control and revision (see working plans, 

control and revision of) 
Control book, 179 

in Austria (management book), 199 

in Prussia, 179 
Coppice, 91, 178, 196 

with standards, 91, 196 
Cork oak, regulation of, 90 
Correlation of age and diameter, 154 
Cotta, 182 

Crown spread (see Gazin), 138 
Current annual increment, 131, 140 
Cutting and planting record (see control 

book) 
Cutting cycle, 28, 109 

and cut per acre, no 

illustration of, 118 

illustration of in normal forest, 112 

intermittent yields in, 126 

long cutting cycles, 117 

preliminary, 125 

short when possible, 117 

summary, 133, 135 

transitional, 126 
Cutting cycles and felling reserve, regulation 
by, ID I 

formula for regulation of cut, 127 
illustration, 128, 129, 136 

second cutting cycle (trial balance), 172 

shortening of, 163 
Cutting plans, annual in Austria, 199 

in Prussia, 178 
Cutting series (see syn., felling series) 
D'Arcy, W. E., 28 
Density of stand, 159 
Denver, 210 
Department of Agriculture, 7 

Secretary of, 7 
Determination of cut, 68 

by area (fixed). 90 

by area allotment, 91 

by area and volume by age classes (stand 
selection). 95 

by area and volume allotment, 93 

by area-volume allotment, 93 

by stem space, 88 

by volume-allotment, 93 

by volume-diameter classes, 88 

by volume-growing stock, 75 

by volume-growing stock-size classes, 82 

by volume-growing stock-increment, 79, 80 
distinction between formulae, 79 

by volume-increment, 78 

by volume-single trees, 86 

classification, 71, jz, 74 

compared, 161 

formulae omitted, y2 

in European countries, 
Alsace-Lorraine, 196 
Austria, 198 
Baden, 188 



214 



American Forest Regulation 



Bavaria, i8i 

France, 200 

Grand Duchy of Hesse, 191 

Grand Duchy of Saxony, 193 

Kingdom of Saxony, 183 

Prussia, 178 

Wiirtemberg, 187 

on National Forests (1921), 210 

summary, 74 
Devastation of forests (see also overcut- 

ting), 2, 9, 12-14, 142 
Diameter-class method, determination of cut 

by (see Hufnagl) 
Diameter limit, determination of cut by 

(see Pinchot-Graves), 88 
District (see adm. subdivision), defined and 
discussed, 26 

ranger, 26 

patrol, 26 
District, forester, 26 

block (see block) 
Divisions (see also subdivisions), 20 

compartment (see compartment) 

in Alsace-Lorraine, 194 

in Austria, 196 

in Baden. 188 

in Bavaria, 180 

in France, 200 

in Grand Duchy of Hesse, 190 

in Grand Duchy of Saxony, 192 

in Kingdom of Saxony, 182 

in Prussia, 176 

in Wiirtemberg, 185 

lot (see lot) 

subcompartment (see lot) 

working circle (see working circle) 

working group (see working group) 
Dixon, 206 

Douglas fir, sj, 50, 211 
Eastern Lassen working circle, 210 
Eastern mixed hardwoods, 166, 168 
Economic rotation (see rotation) 
Eldredge, 69, 206 
Empirical yield tables, 148 
Endres, M., preface, 28, 33. 35, 40, 41, 52, 200 
Estimates (see timber estimates) 
Even-aged forests, in 
European timber market, 203 
Expectancy value, 44 
Felling age (see rotation), 28 
Felling reserve, 131 
Felling budget (see cutting plan) 
Felling series (see syn. cutting series), 97, 

183 
Fernovv, B. E. (author of Introductory 

Note), 6, 14, 58, 175 
Figures, list of in text, 
Financial rotations (see rotation) 
Fisher. W. R., 18 
Fixed area, determination of cut by, 90 

illustration of, 91 

summary, 90 
Flury, 65 
Fole}', John, 6 
Forest (see adm. subdivisions), defined and 

discussed, 26 
Forests, 

even-aged, in 

many-aged, in 

ultimate form, 113 



Forest description and survey, 

in Alsace-Lorraine, 195 

in Austria, 107 

in Baden, 188 

in Bavaria, 181 

in France, 200 

in Grand Duchy of Hesse, 190 

in Grand Duchy of Saxony, 193 

in Kingdom of Saxony, 183 

in Prussia, 177 

in Wiirtemberg, 186 
Forest devastation (see devastation) 
Forest economics, defined, i 
Forest economy, defined, i 
Forest finance, defined, i 
Forest management, defined, i 

in Alsace-Lorraine, 194 

in Austria, 196 

in Baden, 188 

in Bavaria, 180 

in France, 200 

in Grand Duchy of Hesse, 189 

in Grand Duchy of Saxony, 192 

in Kingdom of Saxony, 182 

in Prussia, 175 

in Wiirtemberg, 185 
Forest mensuration, defined, i 
Forest organization (see regulation) 
Forest organizer (see working plans officer 

in appendix A (a).) 
Forest regulation (syn. forest organization. 

See regulation) 
Forest rent (see financial rotations) 
Forest Service, 6, 205, 210 
Forest surveys (see description and surveys) 
Formula methods (see determination of cut) 
French method of 1883, determination of 
cut by, 82, 143 

discussion, 82 

illustration, 85 

summary, 84 
Frothingham, E. H., 34, 36, 46, 62 
Goal of private owners, 107 

of public management, 108 
Gazin, stem space method (see also crown 

spread), 88 
Graves, Henry S., 5, 37, 126 
Grazing, 12 

Grebanare, forest of, 203 
Grebe, 193 

Greeley, W. B., 12. 16 
• Group selection forests, 160 
Growth on cut over lands, 109 

balances decadence, 127 

on virgin forests, no 
Growing stock, actual (see Austrian method, 
etc.) 

normal (see normal growing stock) 
Growth percent, 131 
Guise. C. H., 73 
Gurnaud. 78 
Hansen, T. S., Preface 
Hanzlik, E. J.. Preface, 51, 211 
Hapham, E. E., 16 
Hartig, G. L., 174 
Harvard forest, 7, 97, 204 
Hawley, R. C., 7, 37 
Hess, 206 

Heyer's Method, determination of cut by, 
Introductory Note, 73, 82 



Index 



2>5 



application to America (see Introductory 
Note) 
Hill, R. T., II, 12 
Horizontal cut, 114, 115, 117, 119 

computing cut by, 119 
Hopping, 206 
Hufnagl's method of determining cut, 7^, 

82, loi, 211 
Huffel, 3, 15, 88 
Hundeshagen's method, determination of cut 

by, 72, 79 
Hutton, G. VV., 16 
Increment, current annual, 131, 140 

determination of (see yield tables) 

determination of cut by, 78 

in quality percent, 198 

mean annual, 149 

normal, 58 

price, 203 

quality, 198, 203 

volume (see determination of cut, by 
volume) 
Index, per cent, 198 

Indian single tree method, determination of 
cut by, 86 

illustration, 87 

summary, 87 
Introductory Note (by Fernow), 15 
Introduction, Chapter i, i 
Inyo, management policy stated, 205 
Jones, T. J., 208 

Journal, for records, in Austria, 199 
Judeich, 3 
Karl's method, determination of cut by, 79 

conditions in Alsace-Lorraine, 204 
Kirkland, B. P., 14, 15 
Kissen, Grand Duchy of, 202 
Klein, market, 204 
Koch, E., Preface 
Korstian, C. F., 31, ^2, 43 
Kraft, 201, 203 
Land classification, 4 
Land policy, 11 
Ledger, in Prussia, 179 

Limitation of annual cut on National For- 
ests (by Secretary), 7 
Loblolly pine, 47 
Lodgepole pine, 36. 65. 135, 170 
Logging unit (see block) 
Long, W. H., 33 
Loss of numbers, 141 
Lot (sj'n. subcompartment), defined, 24 

discussed, 25 
Lumbering, effect of on management, 12 

plan (see working plan) 

subdivision, 20 
Management plans (see working plan), 210 
Manual, Forest Service, 7 
Many-aged forests, 11 1, 137 
Maps and tables (see tables) 
Margolin, L., 204 

Markets, influence of on sustained yield, 12 
Market unit (see working circle) 
Martin, H., Preface, 3, 201 
Mason, D. T., 36, 65, 170 
Masson, formula, determination of cut by, 

72. 75 
Mattoon, W. R., 37, 50 

Mean annual increment (see increment), 
149 



Meiriecke, E. P., 33 

Method of 1883, determination of cut by 

(see French method), 82. 143 
Methode du controle, determination of cut 

by (see Gurnaud) 
Minimum exploitable age, efifect of mature 

surplus on, 116 
Missoula, 210 

Moore, Earrington, 5, 17, 71, 86 
Munger, T. T., Preface, 35, 64 
National forest manual (see Manual) 
National forests, 26 
Net income, in Baden, 189 
N. H. Forestry Commission, 46, 204 
New Haven Water Co. tract, 7, 37 
Normal age class distribution, 56 
Normal forest, defined, 56 

abnormality, 56 

age classes in, 57 

artificial and natural factors, 57 

determination of, 141 

discussed, 56 

Flury's formula, 65 

formulae, 59, 62 

illustrations, 62 

importance of, 66 

lodgepole pine calculation, 65 

Munger formula, 64 

relation of growth to cut in, 120 

transitional cutting cycle in, 112 
Normal growing stock, 58, 66 
Normal increment, 58 
Norway pine, 37 
Oak, 34 
Ogden, 210 
Olmstead, F. E., 6 
Organization (see regulation) 
Overcutting, (see also devastation), 142 
Period methods, determination of cut by 

area-period, 91 

area-volume period, 93 

in Alsace-Lorraine, 195 

in Baden, 188 

in Bavaria, 181 

in France, 200 

in Grand Duchy of Hesse, 191 

in Grand Duchy of Saxony, 193 

in Kingdom of Saxony, 182 

in Prussia, 175 

in Wiirtemberg, 185 

volume-period, 93 
Period of financial cutting, 203 
Periodic plan (see working pfans), 5 
Pinchot, 88, 126 
Pisgah National Forest, 7, 116 
Pilz, S3 

Planting plans (see appendix A (a)) 
Policy statements, for National Forests, 7, 

205, 210 
Portland, 211 
Potter, A. F., 12 ' 
Preface, 5 
Preliminary plans in United States, 7, 205, 

210 
Pressler's formula, use of in Austria, 198 
Price Increment, 198 
Production, curtailment of, 10 

continuous, 11 
Prussia, practice of working plans in, 175 
Public ownership, 13 



2l6 



American Forest Regulation 



Public lands com., ii 
Purchase of timber, 115 
Quantitative rotation (see rotations) 
Quiz, 7, 18. 26, 38, 54, 66, 89, 103, 122, 146, 

164, 174 
Rate of interest, 44 
Recknagel, references to works of, 21, 33, 

53. 54. 65, 73, 78, 80 
Reduction per cent, 135 
Regulation (syn. organization) (see also 
determination of cut), i 
American method of, 143 
area methods, 90 
background, 9 
basic conditions, 9 
basic studies, 10 
classification, 71, 72 
compromises necessary, 70 
conception in Europe, 3 
control of in Europe (see working plans) 
coordination with silvics, 170 
correlation, 169 
defined and explained, i 
even-aged stands. 166 
formulae omitted, 72 
goal, 108 

influences determining initial cut, 108 
obstacles, 106 
of cork oak, 90 
of cut, defined, 68, 71 
of basic policy, 68 
of selection forests, 139 
of thinnings, etc., 74, 187, 192 
of transition forests, 126 
of turpentine forests, 90 
of woodlots, 90 
on private property, 7 
policy re ownership, 107 
preliminary requirements, 105 
relation between increment and growing 

stock, 70 
scope of, 4 

summary of principles, 123, 133, 173 
volume methods, 74 
with clear cutting, 103 
with selection cutting, 103 
Research, need of, 10 

Residual growing stock (and felling re- 
serve), 112 
Rotations defined, 28 
and cutting cycles, 113 
basic policy, 30 

economic (or quantitative) rotations, de- 
fined and discussed, 34 
choice of, 35 
illustrations, 35 
final choice of, 51 
financial rotations, defined, 39 
forest rent, defined, 39 

distinguished from soil rent, 41 
soil rent, defined, 39. 200 
discussed. 43 

distinguished from forest rent, 41 
illustrations, 46 
influence of final yield, 45 
rate of interest in, 45 
justify working groups, 23 
kinds of, 30 
length discussed, 29 
mean for stands, 30 



silvicultural. defined and discussed, 32 

illustrations, 33 
statistics, 35, 40, 41 
technical rotations, defined and discussed, 

illustrations, 31 
summary, 52 
Roth, P., references to works of, 3. 10, 21, 

33, 45, 53, 77, 79 
Sale policy, 7, 205, 210 
Savoie. results of working plans in, 208 
Schafifer, 77, 82, 208 
San Francisco, 210 
Schiflfel, G. A., 54 
Schlich, W., Preface, 21, 32, 43, 52, 60, 64, 

77, 86, 91 
Schmidt, 202 
Schuberg, 35 
Schultz, 202 
Schwappach, A., 35 
Secretary of Agriculture, 7 
Selection forests, regulation of, 139 
Shortleaf pine, 37 
Silvicultural system, 22 
Silvicultural rotation (see rotations) 
Soil rent (see financial rotations). 200 
Stand selection method, determination of 
cut by, definition. 95 

compared with allotment methods, 100 

illustration, 95 

table, 153 

summary. 95 
Statistics 

financial, 202, 203 

in Austria, 200 

in Baden, 188 

in France, 200 

in Kingdom of Saxony, 184 

in Wiirtemberg, 187 

rotations, 35 
Sterrett, W. F., 48 
Stock table (see tables) 
Stock taking, 6 
Stoetzer, 3 

Subcompartment (see lot) 
Subdivisions of a forest (see also adm. sub- 
division and management subdivi- 
. sion), 20 

definition of, 20 

size, 20 
Survey of area (see description and survey) 
Sustained yield, application of, 15 

defined, 14 

difficulties, 17, 106 

financial aspect of, .15 

French conditions compared. 15 

limitations in practice, 17, 18 

objective, 17 

on public forests, 16 

ultimate problem, 147-165 
Swiss method (see Gurnaud), 72, 78 
Symbols used. 13 
Tables (examples of in working plans) 

in Austria. 197 

in Grand Duchy of Hesse, 190 

in Grand Duchy of Saxony, 193 

in France, 200 

in Wiirtemberg, 186 

list of, in text, 14 
Technical rotation (see rotations) 



Index 



217 



Terminology Committee, Preface, 25 
Thinnings, regulated by area, 74, 187, 192 
Timber estimates (see also description and 
survey), 6 

cost of, 210 
Toumey, J. W., dedication, 13 
Transitional forest regulation (see Part II) 
Turpentine forest, regulation of, 90 
Tusayan. regulation of, 136 
Unit of regulation (see working circle) 
Use per cent (see Hundeshagen) 
Use of forest land (see land classification) 
Values, definition of kinds of, 39, 40 
Value increment (see increment) ^ 

Vanderbilt property, 7, 116 
Virgin forests, no 
Volume increment (see increment) 
Von Guttenberg, 3 
Von Mantel's method, determination of cut 

by, 75, 128, 150, 211 

correction factor, 76 

illustration, 77 

summary, 77 
Walter, 203 
Washington, D. C, 211 
Watson, R., 10, 11 
Weber, 43 

Western hemlock, 46 
Western white pine, 36 
Western yellow pine, 31, 118, 128, 129, 148, 

154, 210 
White fir, 3;^ 
White pine, 46, 49, 50 
Wimmennaur, 202 
Wolff, M. H., Preface, 24, 212 
Wood-lots, regulation of, 90 
Woodruflf. G. W., 12 

Woolsey, T. S., Jr., references to works of, 
17, 26, 28, 29, 31, 32, 37, go, 93, 156, 
200 
Working circle, 20, 21, 22, 23 
Working figure (see working circle) 
Working group. 20, 21, 22 
Working period (see allotment) 



Working plans, defined, 5 
conferences, 175, 181, 188 
control and revision of 
in Alsace-Lorraine, 196 
in Austria, 199, 200 
in Baden, 188 
in Bavaria, 182 
in France, 200 

in Grand Duchy of Hesse, 192 
in Grand Duchy of Saxony, 194 
in Kingdom of Saxony, 185 
in Prussia, 179 
in Wiirtemberg, 187 
documents (see Chamonix) 
foundations of, 9, etc. 
national forest plans, 210 
outlines for (see France), 200 
practice and policy of 
in Alsace-Lorraine, 194 
in Austria, 196 
in Baden, 188 
in Bavaria, 180 
in France, 200 

in Grand Duchy of Hesse, 189 
in Grand Duchy of Saxony, 192 
in Kingdom of Saxony, 182 
in Prussia, 175 
in United States Forest Service, 5, 205, 

210 
in Wiirtemberg, 185 
progress of, 5 
results of, in Savoie, 208 
uses of forest land (see land classification) 
Working plan manual (see manual) 
Working plan unit (see working circle) 
Working section (see working group) 
Working unit (see working circle) 
Yellow poplar, 138 
Yield, prediction of, 159 
Yield tables, use of in regulation, 92, 137, 

148, 152 
Yale, 7 
Zon, R., 13. 33 



